1
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Yamamoto S, Gaillard J, Vianay B, Guerin C, Orhant-Prioux M, Blanchoin L, Théry M. Actin network architecture can ensure robust centering or sensitive decentering of the centrosome. EMBO J 2022; 41:e111631. [PMID: 35916262 PMCID: PMC9574749 DOI: 10.15252/embj.2022111631] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/24/2022] [Accepted: 07/06/2022] [Indexed: 01/17/2023] Open
Abstract
The orientation of cell polarity depends on the position of the centrosome, the main microtubule-organizing center (MTOC). Microtubules (MTs) transmit pushing forces to the MTOC as they grow against the cell periphery. How the actin network regulates these forces remains unclear. Here, in a cell-free assay, we used purified proteins to reconstitute the interaction of a microtubule aster with actin networks of various architectures in cell-sized microwells. In the absence of actin filaments, MTOC positioning was highly sensitive to variations in microtubule length. The presence of a bulk actin network limited microtubule displacement, and MTOCs were held in place. In contrast, the assembly of a branched actin network along the well edges centered the MTOCs by maintaining an isotropic balance of pushing forces. An anisotropic peripheral actin network caused the MTOC to decenter by focusing the pushing forces. Overall, our results show that actin networks can limit the sensitivity of MTOC positioning to microtubule length and enforce robust MTOC centering or decentering depending on the isotropy of its architecture.
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Affiliation(s)
- Shohei Yamamoto
- Interdisciplinary Research Institute of Grenoble, UMR5168-LPCV, CytoMorpho Lab, University of Grenoble-Alpes, CEA, CNRS, INRA, Grenoble, France
| | - Jérémie Gaillard
- Interdisciplinary Research Institute of Grenoble, UMR5168-LPCV, CytoMorpho Lab, University of Grenoble-Alpes, CEA, CNRS, INRA, Grenoble, France
| | - Benoit Vianay
- Institut de Recherche Saint Louis, UMRS1160-HIPI, CytoMorpho Lab, University of Paris, CEA, INSERM, Paris, France
| | - Christophe Guerin
- Interdisciplinary Research Institute of Grenoble, UMR5168-LPCV, CytoMorpho Lab, University of Grenoble-Alpes, CEA, CNRS, INRA, Grenoble, France
| | - Magali Orhant-Prioux
- Interdisciplinary Research Institute of Grenoble, UMR5168-LPCV, CytoMorpho Lab, University of Grenoble-Alpes, CEA, CNRS, INRA, Grenoble, France
| | - Laurent Blanchoin
- Interdisciplinary Research Institute of Grenoble, UMR5168-LPCV, CytoMorpho Lab, University of Grenoble-Alpes, CEA, CNRS, INRA, Grenoble, France.,Institut de Recherche Saint Louis, UMRS1160-HIPI, CytoMorpho Lab, University of Paris, CEA, INSERM, Paris, France
| | - Manuel Théry
- Interdisciplinary Research Institute of Grenoble, UMR5168-LPCV, CytoMorpho Lab, University of Grenoble-Alpes, CEA, CNRS, INRA, Grenoble, France.,Institut de Recherche Saint Louis, UMRS1160-HIPI, CytoMorpho Lab, University of Paris, CEA, INSERM, Paris, France
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2
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Li C, Zhang X, Dong M, Han X. Progress on Crowding Effect in Cell-like Structures. MEMBRANES 2022; 12:membranes12060593. [PMID: 35736300 PMCID: PMC9228500 DOI: 10.3390/membranes12060593] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 05/27/2022] [Accepted: 05/30/2022] [Indexed: 12/10/2022]
Abstract
Several biological macromolecules, such as proteins, nucleic acids, and polysaccharides, occupy about 30% of the space in cells, resulting in a crowded macromolecule environment. The crowding effect within cells exerts an impact on the functions of biological components, the assembly behavior of biomacromolecules, and the thermodynamics and kinetics of metabolic reactions. Cell-like structures provide confined and independent compartments for studying the working mechanisms of cells, which can be used to study the physiological functions arising from the crowding effect of macromolecules in cells. This article mainly summarizes the progress of research on the macromolecular crowding effects in cell-like structures. It includes the effects of this crowding on actin assembly behavior, tubulin aggregation behavior, and gene expression. The challenges and future trends in this field are presented at the end of the paper.
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Affiliation(s)
- Chao Li
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 92 West Da-Zhi Street, Harbin 150001, China; (C.L.); (X.Z.)
| | - Xiangxiang Zhang
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 92 West Da-Zhi Street, Harbin 150001, China; (C.L.); (X.Z.)
| | - Mingdong Dong
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus, Denmark
- Correspondence: (M.D.); (X.H.)
| | - Xiaojun Han
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 92 West Da-Zhi Street, Harbin 150001, China; (C.L.); (X.Z.)
- Correspondence: (M.D.); (X.H.)
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3
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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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4
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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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5
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Gai Y, Cook B, Setru S, Stone HA, Petry S. Confinement size determines the architecture of Ran-induced microtubule networks. SOFT MATTER 2021; 17:5921-5931. [PMID: 34041514 PMCID: PMC8958645 DOI: 10.1039/d1sm00045d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The organization of microtubules (MTs) is critical for cells during interphase and mitosis. During mitotic spindle assembly, MTs are made and organized around chromosomes in a process regulated by RanGTP. The role of RanGTP has been explored in Xenopus egg extracts, which are not limited by a cell membrane. Here, we investigated whether cell-sized confinements affect the assembly of RanGTP-induced MT networks in Xenopus egg extracts. We used microfluidics to encapsulate extracts within monodisperse extract-in-oil droplets. Importantly, we find that the architecture of Ran-induced MT networks depends on the droplet diameter and the Ran concentration, and differs from structures formed in bulk extracts. Our results highlight that both MT nucleation and physical confinement play critical roles in determining the spatial organization of the MT cytoskeleton.
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Affiliation(s)
- Ya Gai
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, USA.
| | - Brian Cook
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.
| | - Sagar Setru
- Lewis-Sigler Institute of Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Howard A Stone
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, USA.
| | - Sabine Petry
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.
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6
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Bermudez JG, Deiters A, Good MC. Patterning Microtubule Network Organization Reshapes Cell-Like Compartments. ACS Synth Biol 2021; 10:1338-1350. [PMID: 33988978 DOI: 10.1021/acssynbio.0c00575] [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] [Indexed: 11/28/2022]
Abstract
Eukaryotic cells contain a cytoskeletal network comprised of dynamic microtubule filaments whose spatial organization is highly plastic. Specialized microtubule architectures are optimized for different cell types and remodel with the oscillatory cell cycle. These spatially distinct microtubule networks are thought to arise from the activity and localization of microtubule regulators and motors and are further shaped by physical forces from the cell boundary. Given complexities and redundancies of a living cell, it is challenging to disentangle the separate biochemical and physical contributions to microtubule network organization. Therefore, we sought to develop a minimal cell-like system to manipulate and spatially pattern the organization of cytoskeletal components in real-time, providing an opportunity to build distinct spatial structures and to determine how they are shaped by or reshape cell boundaries. We constructed a system for induced spatial patterning of protein components within cell-sized emulsion compartments and used it to drive microtubule network organization in real-time. We controlled dynamic protein relocalization using small molecules and light and slowed lateral diffusion within the lipid monolayer to create stable micropatterns with focused illumination. By fusing microtubule interacting proteins to optochemical dimerization domains, we directed the spatial organization of microtubule networks. Cortical patterning of polymerizing microtubules leads to symmetry breaking and forces that dramatically reshape the compartment. Our system has applications in cell biology to characterize the contributions of biochemical components and physical boundary conditions to microtubule network organization. Additionally, active shape control has uses in protocell engineering and for augmenting the functionalities of synthetic cells.
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Affiliation(s)
- Jessica G. Bermudez
- Bioengineering Graduate Program, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Alexander Deiters
- Chemistry Department, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Matthew C. Good
- Bioengineering Graduate Program, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Cell and Developmental Biology Department, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Bioengineering Department, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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7
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Agarwal S, Klocke MA, Pungchai PE, Franco E. Dynamic self-assembly of compartmentalized DNA nanotubes. Nat Commun 2021; 12:3557. [PMID: 34117248 PMCID: PMC8196065 DOI: 10.1038/s41467-021-23850-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 05/20/2021] [Indexed: 02/05/2023] Open
Abstract
Bottom-up synthetic biology aims to engineer artificial cells capable of responsive behaviors by using a minimal set of molecular components. An important challenge toward this goal is the development of programmable biomaterials that can provide active spatial organization in cell-sized compartments. Here, we demonstrate the dynamic self-assembly of nucleic acid (NA) nanotubes inside water-in-oil droplets. We develop methods to encapsulate and assemble different types of DNA nanotubes from programmable DNA monomers, and demonstrate temporal control of assembly via designed pathways of RNA production and degradation. We examine the dynamic response of encapsulated nanotube assembly and disassembly with the support of statistical analysis of droplet images. Our study provides a toolkit of methods and components to build increasingly complex and functional NA materials to mimic life-like functions in synthetic cells.
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Affiliation(s)
- Siddharth Agarwal
- Department of Bioengineering, University of California, Los Angeles, CA, USA
| | - Melissa A Klocke
- Department of Mechanical Engineering, University of California, Riverside, CA, USA
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA, USA
| | - Passa E Pungchai
- Department of Bioengineering, University of California, Los Angeles, CA, USA
| | - Elisa Franco
- Department of Bioengineering, University of California, Los Angeles, CA, USA.
- Department of Mechanical Engineering, University of California, Riverside, CA, USA.
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA, USA.
- Molecular Biology Institute, University of California, Los Angeles, CA, USA.
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8
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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: 63] [Impact Index Per Article: 21.0] [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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9
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Gavriljuk K, Scocozza B, Ghasemalizadeh F, Seidel H, Nandan AP, Campos-Medina M, Schmick M, Koseska A, Bastiaens PIH. A self-organized synthetic morphogenic liposome responds with shape changes to local light cues. Nat Commun 2021; 12:1548. [PMID: 33750780 PMCID: PMC7943604 DOI: 10.1038/s41467-021-21679-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 01/29/2021] [Indexed: 12/02/2022] Open
Abstract
Reconstituting artificial proto-cells capable of transducing extracellular signals into cytoskeletal changes can reveal fundamental principles of how non-equilibrium phenomena in cellular signal transduction affect morphogenesis. Here, we generated a Synthetic Morphogenic Membrane System (SynMMS) by encapsulating a dynamic microtubule (MT) aster and a light-inducible signaling system driven by GTP/ATP chemical potential into cell-sized liposomes. Responding to light cues in analogy to morphogens, this biomimetic design embodies basic principles of localized Rho-GTPase signal transduction that generate an intracellular MT-regulator signaling gradient. Light-induced signaling promotes membrane-deforming growth of MT-filaments by dynamically elevating the membrane-proximal tubulin concentration. The resulting membrane deformations enable recursive coupling of the MT-aster with the signaling system, which generates global self-organized morphologies that reorganize towards local external cues in dependence on prior shape. SynMMS thereby signifies a step towards bio-inspired engineering of self-organized cellular morphogenesis. The authors generated a Synthetic Morphogenic Membrane System by encapsulating a dynamic microtubule aster and a light-inducible signaling system driven by GTP/ATP chemical potential into cell-sized liposomes. This reconstitution of artificial proto-cells reveals how non-equilibrium phenomena affect cellular information processing in morphogenesis.
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Affiliation(s)
- Konstantin Gavriljuk
- Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany
| | - Bruno Scocozza
- Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany
| | - Farid Ghasemalizadeh
- Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany
| | - Hans Seidel
- Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany
| | - Akhilesh P Nandan
- Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany.,Cellular Computations and Learning, Center of Advanced European Studies and Research (caesar), Bonn, Germany
| | - Manuel Campos-Medina
- Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany
| | - Malte Schmick
- Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany
| | - Aneta Koseska
- Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany.,Cellular Computations and Learning, Center of Advanced European Studies and Research (caesar), Bonn, Germany
| | - Philippe I H Bastiaens
- Department of Systemic Cell Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany. .,Faculty of Chemistry and Chemical Biology, TU Dortmund, Dortmund, Germany.
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10
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In Vitro Reconstitution of Dynamic Co-organization of Microtubules and Actin Filaments in Emulsion Droplets. Methods Mol Biol 2021. [PMID: 31879898 DOI: 10.1007/978-1-0716-0219-5_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
In vitro (or cell-free) reconstitution is a powerful tool to study the physical basis of cytoskeletal organization in eukaryotic cells. Cytoskeletal reconstitution studies have mostly been done for individual cytoskeleton systems in unconfined 3D or quasi-2D geometries, which lack complexity relative to a cellular environment. To increase the level of complexity, we present a method to study co-organization of two cytoskeletal components, namely microtubules and actin filaments, confined in cell-sized water-in-oil emulsion droplets. We show that centrosome-nucleated dynamic microtubules can be made to interact with actin filaments through a tip-tracking complex consisting of microtubule end-binding proteins and an actin-microtubule cytolinker. In addition to the protocols themselves, we discuss the optimization steps required in order to build these more complex in vitro model systems of cytoskeletal interactions.
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11
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Khetan N, Athale CA. Aster swarming by symmetry breaking of cortical dynein transport and coupling kinesins. SOFT MATTER 2020; 16:8554-8564. [PMID: 32840555 DOI: 10.1039/d0sm01086c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Microtubule (MT) radial arrays or asters establish the internal topology of a cell by interacting with organelles and molecular motors. We proceed to understand the general pattern forming potential of aster-motor systems using a computational model of multiple MT asters interacting with motors in cellular confinement. In this model dynein motors are attached to the cell cortex and plus-ended motors resembling kinesin-5 diffuse in the cell interior. The introduction of 'noise' in the form of MT length fluctuations spontaneously results in the emergence of coordinated, achiral vortex-like rotation of asters. The coherence and persistence of rotation require a threshold density of both cortical dyneins and coupling kinesins, while the onset is diffusion-limited with relation to the cortical dynein mobility. The coordinated rotational motion emerges due to the resolution of a 'tug-of-war' of multiple cortical dynein motors bound to MTs of the same aster by 'noise' in the form of MT dynamic instability. This transient symmetry breaking is amplified by local coupling by kinesin-5 complexes. The lack of widespread aster rotation across cell types suggests that biophysical mechanisms that suppress such intrinsic dynamics may have evolved. This model is analogous to more general models of locally coupled self-propelled particles (SPP) that spontaneously undergo collective transport in the presence of 'noise' that have been invoked to explain swarming in birds and fish. However, the aster-motor system is distinct from SPP models with regard to the particle density and 'noise' dependence, providing a set of experimentally testable predictions for a novel sub-cellular pattern forming system.
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Affiliation(s)
- Neha Khetan
- Div. of Biology, IISER Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
| | - Chaitanya A Athale
- Div. of Biology, IISER Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
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12
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Bashirzadeh Y, Liu AP. Encapsulation of the cytoskeleton: towards mimicking the mechanics of a cell. SOFT MATTER 2019; 15:8425-8436. [PMID: 31621750 DOI: 10.1039/c9sm01669d] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The cytoskeleton of a cell controls all the aspects of cell shape changes and motility from its physiological functions for survival to reproduction to death. The structure and dynamics of the cytoskeletal components: actin, microtubules, intermediate filaments, and septins - recently regarded as the fourth member of the cytoskeleton family - are conserved during evolution. Such conserved and effective control over the mechanics of the cell makes the cytoskeletal components great candidates for in vitro reconstitution and bottom-up synthetic biology studies. Here, we review the recent efforts in reconstitution of the cytoskeleton in and on membrane-enclosed biomimetic systems and argue that co-reconstitution and synergistic interplay between cytoskeletal filaments might be indispensable for efficient mechanical functionality of active minimal cells. Further, mechanical equilibrium in adherent eukaryotic cells is achieved by the formation of integrin-based focal contacts with extracellular matrix (ECM) and the transmission of stresses generated by actomyosin contraction to ECM. Therefore, a minimal mimic of such balance of forces and quasi-static kinetics of the cell by bottom-up reconstitution requires a careful construction of contractile machineries and their link with adhesive contacts. In this review, in addition to cytoskeletal crosstalk, we provide a perspective on reconstruction of cell mechanical equilibrium by reconstitution of cortical actomyosin networks in lipid membrane vesicles adhered on compliant substrates and also discuss future perspectives of this active research area.
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Affiliation(s)
- Yashar Bashirzadeh
- Department of Mechanical Engineering, University of Michigan, 2350 Hayward Street, Ann Arbor, Michigan, USA.
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13
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Vendel KJA, Tschirpke S, Shamsi F, Dogterom M, Laan L. Minimal in vitro systems shed light on cell polarity. J Cell Sci 2019; 132:132/4/jcs217554. [PMID: 30700498 DOI: 10.1242/jcs.217554] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cell polarity - the morphological and functional differentiation of cellular compartments in a directional manner - is required for processes such as orientation of cell division, directed cellular growth and motility. How the interplay of components within the complexity of a cell leads to cell polarity is still heavily debated. In this Review, we focus on one specific aspect of cell polarity: the non-uniform accumulation of proteins on the cell membrane. In cells, this is achieved through reaction-diffusion and/or cytoskeleton-based mechanisms. In reaction-diffusion systems, components are transformed into each other by chemical reactions and are moving through space by diffusion. In cytoskeleton-based processes, cellular components (i.e. proteins) are actively transported by microtubules (MTs) and actin filaments to specific locations in the cell. We examine how minimal systems - in vitro reconstitutions of a particular cellular function with a minimal number of components - are designed, how they contribute to our understanding of cell polarity (i.e. protein accumulation), and how they complement in vivo investigations. We start by discussing the Min protein system from Escherichia coli, which represents a reaction-diffusion system with a well-established minimal system. This is followed by a discussion of MT-based directed transport for cell polarity markers as an example of a cytoskeleton-based mechanism. To conclude, we discuss, as an example, the interplay of reaction-diffusion and cytoskeleton-based mechanisms during polarity establishment in budding yeast.
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Affiliation(s)
- Kim J A Vendel
- Bionanoscience Department, Kavli Institute of Nanoscience, Delft University of Technology, Delft 2600 GA, The Netherlands
| | - Sophie Tschirpke
- Bionanoscience Department, Kavli Institute of Nanoscience, Delft University of Technology, Delft 2600 GA, The Netherlands
| | - Fayezeh Shamsi
- Bionanoscience Department, Kavli Institute of Nanoscience, Delft University of Technology, Delft 2600 GA, The Netherlands
| | - Marileen Dogterom
- Bionanoscience Department, Kavli Institute of Nanoscience, Delft University of Technology, Delft 2600 GA, The Netherlands
| | - Liedewij Laan
- Bionanoscience Department, Kavli Institute of Nanoscience, Delft University of Technology, Delft 2600 GA, The Netherlands
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14
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Roostalu J, Rickman J, Thomas C, Nédélec F, Surrey T. Determinants of Polar versus Nematic Organization in Networks of Dynamic Microtubules and Mitotic Motors. Cell 2018; 175:796-808.e14. [PMID: 30340043 PMCID: PMC6198040 DOI: 10.1016/j.cell.2018.09.029] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 06/25/2018] [Accepted: 09/13/2018] [Indexed: 11/03/2022]
Abstract
During cell division, mitotic motors organize microtubules in the bipolar spindle into either polar arrays at the spindle poles or a "nematic" network of aligned microtubules at the spindle center. The reasons for the distinct self-organizing capacities of dynamic microtubules and different motors are not understood. Using in vitro reconstitution experiments and computer simulations, we show that the human mitotic motors kinesin-5 KIF11 and kinesin-14 HSET, despite opposite directionalities, can both organize dynamic microtubules into either polar or nematic networks. We show that in addition to the motor properties the natural asymmetry between microtubule plus- and minus-end growth critically contributes to the organizational potential of the motors. We identify two control parameters that capture system composition and kinetic properties and predict the outcome of microtubule network organization. These results elucidate a fundamental design principle of spindle bipolarity and establish general rules for active filament network organization.
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Affiliation(s)
| | - Jamie Rickman
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Claire Thomas
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - François Nédélec
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
| | - Thomas Surrey
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
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15
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Juniper MPN, Weiss M, Platzman I, Spatz JP, Surrey T. Spherical network contraction forms microtubule asters in confinement. SOFT MATTER 2018; 14:901-909. [PMID: 29364311 DOI: 10.1039/c7sm01718a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Microtubules and motor proteins form active filament networks that are critical for a variety of functions in living cells. Network topology and dynamics are the result of a self-organisation process that takes place within the boundaries of the cell. Previous biochemical in vitro studies with biomimetic systems consisting of purified motors and microtubules have demonstrated that confinement has an important effect on the outcome of the self-organisation process. However, the pathway of motor/microtubule self-organisation under confinement and its effects on network morphology are still poorly understood. Here, we have investigated how minus-end directed microtubule cross-linking kinesins organise microtubules inside polymer-stabilised microfluidic droplets of well-controlled size. We find that confinement can impose a novel pathway of microtubule aster formation proceeding via the constriction of an initially spherical motor/microtubule network. This mechanism illustrates the close relationship between confinement, network contraction, and aster formation. The spherical constriction pathway robustly produces single, well-centred asters with remarkable reproducibility across thousands of droplets. These results show that the additional constraint of well-defined confinement can improve the robustness of active network self-organisation, providing insight into the design principles of self-organising active networks in micro-scale confinement.
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Affiliation(s)
| | - Marian Weiss
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Germany and Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Ilia Platzman
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Germany and Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Joachim P Spatz
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Germany and Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Thomas Surrey
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
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16
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Tsuji M, Rashedul Kabir AM, Ito M, Inoue D, Kokado K, Sada K, Kakugo A. Motility of Microtubules on the Inner Surface of Water-in-Oil Emulsion Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:12108-12113. [PMID: 28972769 DOI: 10.1021/acs.langmuir.7b01550] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Water-in-oil emulsion systems have recently attracted much attention in various fields. However, functionalization of water-in-oil emulsion systems, which is required for expanding their applications in industries and research, has been challenging. We now demonstrate the functionalization of a water-in-oil emulsion system by anchoring a target protein molecule. A microtubule (MT)-associated motor protein kinesin-1 was successfully anchored to the inner surface of water-in-oil emulsion droplets by employing the specific interaction of nickel-nitrilotriacetic acid-histidine tag. The MTs exhibited a gliding motion on the kinesin-functionalized inner surface of the emulsion droplets, which confirmed the success of the functionalization of the water-in-oil emulsion system. This result would be beneficial in exploring the roles of biomolecular motor systems in the cellular events that take place at the cell membrane and might also contribute to expanding the nanotechnological applications of biomolecular motors and water-in-oil emulsion systems in the future.
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Affiliation(s)
- Mikako Tsuji
- Graduate School of Chemical Sciences and Engineering and ‡Faculty of Science, Hokkaido University , Sapporo 060-0810, Japan
| | - Arif Md Rashedul Kabir
- Graduate School of Chemical Sciences and Engineering and ‡Faculty of Science, Hokkaido University , Sapporo 060-0810, Japan
| | - Masaki Ito
- Graduate School of Chemical Sciences and Engineering and ‡Faculty of Science, Hokkaido University , Sapporo 060-0810, Japan
| | - Daisuke Inoue
- Graduate School of Chemical Sciences and Engineering and ‡Faculty of Science, Hokkaido University , Sapporo 060-0810, Japan
| | - Kenta Kokado
- Graduate School of Chemical Sciences and Engineering and ‡Faculty of Science, Hokkaido University , Sapporo 060-0810, Japan
| | - Kazuki Sada
- Graduate School of Chemical Sciences and Engineering and ‡Faculty of Science, Hokkaido University , Sapporo 060-0810, Japan
| | - Akira Kakugo
- Graduate School of Chemical Sciences and Engineering and ‡Faculty of Science, Hokkaido University , Sapporo 060-0810, Japan
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17
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Bermudez JG, Chen H, Einstein LC, Good MC. Probing the biology of cell boundary conditions through confinement of Xenopus cell-free cytoplasmic extracts. Genesis 2017; 55. [PMID: 28132422 DOI: 10.1002/dvg.23013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 12/04/2016] [Accepted: 12/05/2016] [Indexed: 11/11/2022]
Abstract
Cell-free cytoplasmic extracts prepared from Xenopus eggs and embryos have for decades provided a biochemical system with which to interrogate complex cell biological processes in vitro. Recently, the application of microfabrication and microfluidic strategies in biology has narrowed the gap between in vitro and in vivo studies by enabling formation of cell-size compartments containing functional cytoplasm. These approaches provide numerous advantages over traditional biochemical experiments performed in a test tube. Most notably, the cell-free cytoplasm is confined using a two- or three-dimensional boundary, which mimics the natural configuration of a cell. This strategy enables characterization of the spatial organization of a cell, and the role that boundaries play in regulating intracellular assembly and function. In this review, we describe the marriage of Xenopus cell-free cytoplasm and confinement technologies to generate synthetic cell-like systems, the recent biological insights they have enabled, and the promise they hold for future scientific discovery.
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Affiliation(s)
- Jessica G Bermudez
- Department of Bioengineering, University of Pennsylvania, 421 Curie Blvd, 1151 BRB II/III, Philadelphia, Pennsylvania, 19104
| | - Hui Chen
- Department of Cell and Developmental Biology, University of Pennsylvania, 421 Curie Blvd, 1151 BRB II/III, Philadelphia, Pennsylvania, 19104
| | - Lily C Einstein
- Department of Cell and Developmental Biology, University of Pennsylvania, 421 Curie Blvd, 1151 BRB II/III, Philadelphia, Pennsylvania, 19104
| | - Matthew C Good
- Department of Bioengineering, University of Pennsylvania, 421 Curie Blvd, 1151 BRB II/III, Philadelphia, Pennsylvania, 19104.,Department of Cell and Developmental Biology, University of Pennsylvania, 421 Curie Blvd, 1151 BRB II/III, Philadelphia, Pennsylvania, 19104
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18
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Blackwell R, Edelmaier C, Sweezy-Schindler O, Lamson A, Gergely ZR, O’Toole E, Crapo A, Hough LE, McIntosh JR, Glaser MA, Betterton MD. Physical determinants of bipolar mitotic spindle assembly and stability in fission yeast. SCIENCE ADVANCES 2017; 3:e1601603. [PMID: 28116355 PMCID: PMC5249259 DOI: 10.1126/sciadv.1601603] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 12/05/2016] [Indexed: 05/10/2023]
Abstract
Mitotic spindles use an elegant bipolar architecture to segregate duplicated chromosomes with high fidelity. Bipolar spindles form from a monopolar initial condition; this is the most fundamental construction problem that the spindle must solve. Microtubules, motors, and cross-linkers are important for bipolarity, but the mechanisms necessary and sufficient for spindle assembly remain unknown. We describe a physical model that exhibits de novo bipolar spindle formation. We began with physical properties of fission-yeast spindle pole body size and microtubule number, kinesin-5 motors, kinesin-14 motors, and passive cross-linkers. Our model results agree quantitatively with our experiments in fission yeast, thereby establishing a minimal system with which to interrogate collective self-assembly. By varying the features of our model, we identify a set of functions essential for the generation and stability of spindle bipolarity. When kinesin-5 motors are present, their bidirectionality is essential, but spindles can form in the presence of passive cross-linkers alone. We also identify characteristic failed states of spindle assembly-the persistent monopole, X spindle, separated asters, and short spindle, which are avoided by the creation and maintenance of antiparallel microtubule overlaps. Our model can guide the identification of new, multifaceted strategies to induce mitotic catastrophes; these would constitute novel strategies for cancer chemotherapy.
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Affiliation(s)
- Robert Blackwell
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
- PULS Group, Department of Physics and Cluster of Excellence: Engineering of Advanced Materials, Friedrich-Alexander University Erlangen-Nurnberg, Nagelsbachstr. 49b, Erlangen, Germany
| | | | | | - Adam Lamson
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Zachary R. Gergely
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Eileen O’Toole
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Ammon Crapo
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Loren E. Hough
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - J. Richard McIntosh
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Matthew A. Glaser
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Meredith D. Betterton
- Department of Physics, University of Colorado, Boulder, CO 80309, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
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19
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Encapsulation of Xenopus Egg and Embryo Extract Spindle Assembly Reactions in Synthetic Cell-Like Compartments with Tunable Size. Methods Mol Biol 2016; 1413:87-108. [PMID: 27193845 DOI: 10.1007/978-1-4939-3542-0_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Methods are described for preparing Xenopus laevis egg and embryo cytoplasm and encapsulating extract spindle assembly reactions in cell-like compartments to investigate the effects of cell size on intracellular assembly. Cytoplasm prepared from the eggs or embryos of individual frogs is screened for the ability to form interphase nuclei and metaphase spindles, and subsequently packaged, along with DNA, into droplets of varying size using microfluidics. The dimensions of these cell-like droplets are specified to match the range of cell diameters present in early embryo development. The scaling relationship between droplets and spindles is quantified using live fluorescence imaging on a spinning-disk confocal microscope. By comparing the encapsulated assembly of spindles formed from cytoplasmic extracts prepared from embryos at distinct stages of Xenopus early development, the influence of cell composition and cell size on spindle scaling can be evaluated. Because the extract system is biochemically tractable, the function of individual proteins in spindle scaling can be evaluated by supplementing or depleting factors in the cytoplasm.
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20
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Abstract
In living cells, the architecture of the microtubule cytoskeleton is intimately linked to its function. The principles determining how microtubules arrange in space are, however, still not fully understood. Biochemical activities controlling microtubule nucleation and dynamics as well as mechanochemical activities exerted by molecular motors and the dynamic microtubules themselves are known to be critical for the correct spatial organization of the microtubule cytoskeleton. In vitro reconstitution approaches have revealed the morphogenetic properties of these activities in minimal systems. In most cases, such in vitro experiments were performed in experimental chambers of spatial dimensions that exceeded typical cell sizes by orders of magnitude. Here, we describe a method for the fluorescence microscopic study of the effects of spatial confinement on the self-organization of purified motors and microtubules that are encapsulated in micrometer-sized lipid-monolayered droplets emulsified in oil. In the future, this experimental setup can be extended in several ways. Additional proteins can be added, either to the lumen or to the boundary of the microcontainers, and the droplets can be transformed into liposomes. Such more complex in vitro reconstitutions would be another step closer to mimicking intracellular cytoskeleton organization.
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Affiliation(s)
- Hella Baumann
- London Research Institute, Cancer Research UK, London, UK
| | - Thomas Surrey
- London Research Institute, Cancer Research UK, London, UK
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21
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Keber FC, Loiseau E, Sanchez T, DeCamp SJ, Giomi L, Bowick MJ, Marchetti MC, Dogic Z, Bausch AR. Topology and dynamics of active nematic vesicles. Science 2014; 345:1135-9. [PMID: 25190790 DOI: 10.1126/science.1254784] [Citation(s) in RCA: 307] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Engineering synthetic materials that mimic the remarkable complexity of living organisms is a fundamental challenge in science and technology. We studied the spatiotemporal patterns that emerge when an active nematic film of microtubules and molecular motors is encapsulated within a shape-changing lipid vesicle. Unlike in equilibrium systems, where defects are largely static structures, in active nematics defects move spontaneously and can be described as self-propelled particles. The combination of activity, topological constraints, and vesicle deformability produces a myriad of dynamical states. We highlight two dynamical modes: a tunable periodic state that oscillates between two defect configurations, and shape-changing vesicles with streaming filopodia-like protrusions. These results demonstrate how biomimetic materials can be obtained when topological constraints are used to control the non-equilibrium dynamics of active matter.
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Affiliation(s)
- Felix C Keber
- Department of Physics, Technische Universität München, 85748 Garching, Germany. Institute for Advanced Study, Technische Universität München, 85748 Garching, Germany
| | - Etienne Loiseau
- Department of Physics, Technische Universität München, 85748 Garching, Germany
| | - Tim Sanchez
- Department of Physics, Brandeis University, Waltham, MA 02474, USA
| | - Stephen J DeCamp
- Department of Physics, Brandeis University, Waltham, MA 02474, USA
| | - Luca Giomi
- SISSA International School for Advanced Studies, Via Bonomea 265, 34136 Trieste, Italy. Instituut-Lorentz for Theoretical Physics, Leiden University, 2333 CA Leiden, Netherlands
| | - Mark J Bowick
- Physics Department and Syracuse Biomaterials Institute, Syracuse University, Syracuse, NY 13244, USA
| | - M Cristina Marchetti
- Physics Department and Syracuse Biomaterials Institute, Syracuse University, Syracuse, NY 13244, USA
| | - Zvonimir Dogic
- Institute for Advanced Study, Technische Universität München, 85748 Garching, Germany. Department of Physics, Brandeis University, Waltham, MA 02474, USA
| | - Andreas R Bausch
- Department of Physics, Technische Universität München, 85748 Garching, Germany.
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