1
|
Razavi S, Wong F, Abubaker-Sharif B, Matsubayashi HT, Nakamura H, Nguyen NTH, Robinson DN, Chen B, Iglesias PA, Inoue T. Synthetic control of actin polymerization and symmetry breaking in active protocells. SCIENCE ADVANCES 2024; 10:eadk9731. [PMID: 38865458 PMCID: PMC11168455 DOI: 10.1126/sciadv.adk9731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 05/08/2024] [Indexed: 06/14/2024]
Abstract
Nonlinear biomolecular interactions on membranes drive membrane remodeling crucial for biological processes including chemotaxis, cytokinesis, and endocytosis. The complexity of biomolecular interactions, their redundancy, and the importance of spatiotemporal context in membrane organization impede understanding of the physical principles governing membrane mechanics. Developing a minimal in vitro system that mimics molecular signaling and membrane remodeling while maintaining physiological fidelity poses a major challenge. Inspired by chemotaxis, we reconstructed chemically regulated actin polymerization inside vesicles, guiding membrane self-organization. An external, undirected chemical input induced directed actin polymerization and membrane deformation uncorrelated with upstream biochemical cues, suggesting symmetry breaking. A biophysical model incorporating actin dynamics and membrane mechanics proposes that uneven actin distributions cause nonlinear membrane deformations, consistent with experimental findings. This protocellular system illuminates the interplay between actin dynamics and membrane shape during symmetry breaking, offering insights into chemotaxis and other cell biological processes.
Collapse
Affiliation(s)
- Shiva Razavi
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Felix Wong
- Institute for Medical Engineering and Science, Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
| | - Bedri Abubaker-Sharif
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Hideaki T. Matsubayashi
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Hideki Nakamura
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Nhung Thi Hong Nguyen
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Douglas N. Robinson
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Baoyu Chen
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - Pablo A. Iglesias
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Takanari Inoue
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| |
Collapse
|
2
|
Fink A, Fazliev S, Abele T, Spatz JP, Göpfrich K, Cavalcanti-Adam EA. Membrane localization of actin filaments stabilizes giant unilamellar vesicles against external deforming forces. Eur J Cell Biol 2024; 103:151428. [PMID: 38850712 DOI: 10.1016/j.ejcb.2024.151428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 05/25/2024] [Accepted: 06/03/2024] [Indexed: 06/10/2024] Open
Abstract
Actin organization is crucial for establishing cell polarity, which influences processes such as directed cell motility and division. Despite its critical role in living organisms, achieving similar polarity in synthetic cells remains challenging. In this study, we employ a bottom-up approach to investigate how molecular crowders facilitate the formation of cortex-like actin networks and how these networks localize and organize based on membrane shape. Using giant unilamellar vesicles (GUVs) as models for cell membranes, we show that actin filaments can arrange along the membrane to form cortex-like structures. Notably, this organization is achieved using only actin and crowders as a minimal set of components. We utilize surface micropatterning to examine actin filament organization in deformed GUVs adhered to various pattern shapes. Our findings indicate that at the periphery of spherical GUVs, actin bundles align along the membrane. However, in highly curved regions of adhered GUVs, actin bundles avoid crossing the highly curved edges perpendicular to the adhesion site and instead remain in the lower curved regions by aligning parallel to the micropatterned surface. Furthermore, the actin bundles increase the stiffness of the GUVs, effectively counteracting strong deformations when GUVs adhere to micropatterns. This finding is corroborated by real-time deformability cytometry on GUVs with synthetic actin cortices. By precisely manipulating the shape of GUVs, our study provides a minimal system to investigate the interplay between actin structures and the membrane. Our findings provide insights into the spatial organization of actin structures within crowded environments, specifically inside GUVs that resemble the size and shape of cells. This study advances our understanding of actin network organization and functionality within cell-sized compartments.
Collapse
Affiliation(s)
- Andreas Fink
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, Heidelberg 69120, Germany
| | - Sunnatullo Fazliev
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, Heidelberg 69120, Germany
| | - Tobias Abele
- Biophysical Engineering Group, Center for Molecular Biology of Heidelberg University (ZMBH) Heidelberg University, Im Neuenheimer Feld 329, Heidelberg 69120, Germany
| | - Joachim P Spatz
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, Heidelberg 69120, Germany
| | - Kerstin Göpfrich
- Biophysical Engineering Group, Max Planck Institute for Medical Research, Jahnstraße 29, Heidelberg 69120, Germany; Biophysical Engineering Group, Center for Molecular Biology of Heidelberg University (ZMBH) Heidelberg University, Im Neuenheimer Feld 329, Heidelberg 69120, Germany
| | - Elisabetta Ada Cavalcanti-Adam
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, Heidelberg 69120, Germany; Cellular Biomechanics, University of Bayreuth, Universitätsstraße 30, Bayreuth 95447, Germany.
| |
Collapse
|
3
|
Okada S, Shoji K. Microrail-assisted liposome trapping and aligning in microfluidic channels. RSC Adv 2024; 14:18003-18010. [PMID: 38841399 PMCID: PMC11152143 DOI: 10.1039/d4ra02094d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 05/28/2024] [Indexed: 06/07/2024] Open
Abstract
Liposome assemblies with a specific shape are potential cell tissue models for studying intercellular communication. Microfluidic channels that can trap liposomes have been constructed to achieve efficient and high-throughput manipulation and observation of liposomes. However, the trapping and alignment of multiple liposomes in a specific space are still challenging because the liposomes are soft and easily ruptured. In this study, we focused on a microrail-assisted technique for manipulating water-in-oil (w/o) emulsions. In this technique, w/o emulsions are trapped under the microrails through a surface energy gradient. First, we investigated whether the microrail channel can be applied for liposome trapping and alignment and found that the numerical simulations showed that drag forces in the direction of the microrail acted on the liposomes, thereby moving the liposomes from the main channel to the microrail. Next, we designed a microrail device based on the simulation results and trapped liposomes using the device. Resultantly, 24.7 ± 8.5 liposomes were aligned under the microrail within an hour, and the microrail was filled with liposomes for 3 hours. Finally, we prepared the microrail devices with y-shaped and ring-shaped microrails and demonstrated the construction of liposome assemblies with specific shapes, not only the straight shape. Our results indicate that the microrail-assisted technique is a valuable method for manipulating liposomes because it has the potential to provide various-shaped liposome assemblies. We believe the microrail channel will be a powerful tool for constructing liposome-based cell-cell interaction models.
Collapse
Affiliation(s)
- Shun Okada
- Department of Mechanical Engineering, Nagaoka University of Technology 1603-1 Kamitomioka Nagaoka Niigata 940-2188 Japan
| | - Kan Shoji
- Department of Mechanical Engineering, Nagaoka University of Technology 1603-1 Kamitomioka Nagaoka Niigata 940-2188 Japan
| |
Collapse
|
4
|
Chandrasekaran A, Graham K, Stachowiak JC, Rangamani P. Kinetic trapping organizes actin filaments within liquid-like protein droplets. Nat Commun 2024; 15:3139. [PMID: 38605007 PMCID: PMC11009352 DOI: 10.1038/s41467-024-46726-6] [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: 06/05/2023] [Accepted: 03/07/2024] [Indexed: 04/13/2024] Open
Abstract
Several actin-binding proteins (ABPs) phase separate to form condensates capable of curating the actin network shapes. Here, we use computational modeling to understand the principles of actin network organization within VASP condensate droplets. Our simulations reveal that the different actin shapes, namely shells, rings, and mixture states are highly dependent on the kinetics of VASP-actin interactions, suggesting that they arise from kinetic trapping. Specifically, we show that reducing the residence time of VASP on actin filaments reduces degree of bundling, thereby promoting assembly of shells rather than rings. We validate the model predictions experimentally using a VASP-mutant with decreased bundling capability. Finally, we investigate the ring opening within deformed droplets and found that the sphere-to-ellipsoid transition is favored under a wide range of filament lengths while the ellipsoid-to-rod transition is only permitted when filaments have a specific range of lengths. Our findings highlight key mechanisms of actin organization within phase-separated ABPs.
Collapse
Affiliation(s)
- Aravind Chandrasekaran
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, 92093-0411, USA
| | - Kristin Graham
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
| | - Jeanne C Stachowiak
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, 78712, USA.
- Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA.
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, 92093-0411, USA.
| |
Collapse
|
5
|
Waechtler BE, Jayasankar R, Morin EP, Robinson DN. Benefits and challenges of reconstituting the actin cortex. Cytoskeleton (Hoboken) 2024. [PMID: 38520148 DOI: 10.1002/cm.21855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 02/21/2024] [Accepted: 03/05/2024] [Indexed: 03/25/2024]
Abstract
The cell's ability to change shape is a central feature in many cellular processes, including cytokinesis, motility, migration, and tissue formation. The cell constructs a network of contractile proteins underneath the cell membrane to form the cortex, and the reorganization of these components directly contributes to cellular shape changes. The desire to mimic these cell shape changes to aid in the creation of a synthetic cell has been increasing. Therefore, membrane-based reconstitution experiments have flourished, furthering our understanding of the minimal components the cell uses throughout these processes. Although biochemical approaches increased our understanding of actin, myosin II, and actin-associated proteins, using membrane-based reconstituted systems has further expanded our understanding of actin structures and functions because membrane-cortex interactions can be analyzed. In this review, we highlight the recent developments in membrane-based reconstitution techniques. We examine the current findings on the minimal components needed to recapitulate distinct actin structures and functions and how they relate to the cortex's impact on cellular mechanical properties. We also explore how co-processing of computational models with wet-lab experiments enhances our understanding of these properties. Finally, we emphasize the benefits and challenges inherent to membrane-based, reconstitution assays, ranging from the advantage of precise control over the system to the difficulty of integrating these findings into the complex cellular environment.
Collapse
Affiliation(s)
- Brooke E Waechtler
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Rajan Jayasankar
- Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Baltimore, Maryland, USA
| | - Emma P Morin
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Douglas N Robinson
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Baltimore, Maryland, USA
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| |
Collapse
|
6
|
Sakamoto R, Maeda YT. Unveiling the physics underlying symmetry breaking of the actin cytoskeleton: An artificial cell-based approach. Biophys Physicobiol 2023; 20:e200032. [PMID: 38124798 PMCID: PMC10728624 DOI: 10.2142/biophysico.bppb-v20.0032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 08/18/2023] [Indexed: 12/23/2023] Open
Abstract
Single-cell behaviors cover many biological functions, such as cell division during morphogenesis and tissue metastasis, and cell migration during cancer cell invasion and immune cell responses. Symmetry breaking of the positioning of organelles and the cell shape are often associated with these biological functions. One of the main players in symmetry breaking at the cellular scale is the actin cytoskeleton, comprising actin filaments and myosin motors that generate contractile forces. However, because the self-organization of the actomyosin network is regulated by the biochemical signaling in cells, how the mechanical contraction of the actin cytoskeleton induces diverse self-organized behaviors and drives the cell-scale symmetry breaking remains unclear. In recent times, to understand the physical underpinnings of the symmetry breaking exhibited in the actin cytoskeleton, artificial cell models encapsulating the cytoplasmic actomyosin networks covered with lipid monolayers have been developed. By decoupling the actomyosin mechanics from the complex biochemical signaling within living cells, this system allows one to study the self-organization of actomyosin networks confined in cell-sized spaces. We review the recent developments in the physics of confined actomyosin networks and provide future perspectives on the artificial cell-based approach. This review article is an extended version of the Japanese article, The Physical Principle of Cell Migration Under Confinement: Artificial Cell-based Bottom-up Approach, published in SEIBUTSU BUTSURI Vol. 63, p. 163-164 (2023).
Collapse
Affiliation(s)
- Ryota Sakamoto
- Department of Physics, Graduate School of Science, Kyushu University, Fukuoka 819-0395, Japan
- Department of Biomedical Engineering, Yale University, Connecticut 06520, USA
- Systems Biology Institute, Yale University, Connecticut 06516, USA
| | - Yusuke T. Maeda
- Department of Physics, Graduate School of Science, Kyushu University, Fukuoka 819-0395, Japan
| |
Collapse
|
7
|
Geometric trade-off between contractile force and viscous drag determines the actomyosin-based motility of a cell-sized droplet. Proc Natl Acad Sci U S A 2022; 119:e2121147119. [PMID: 35857875 PMCID: PMC9335187 DOI: 10.1073/pnas.2121147119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cell migration in confined environments is fundamental for diverse biological processes from cancer invasion to leukocyte trafficking. The cell body is propelled by the contractile force of actomyosin networks transmitted from the cell membrane to the external substrates. However, physical determinants of actomyosin-based migration capacity in confined environments are not fully understood. Here, we develop an in vitro migratory cell model, where cytoplasmic actomyosin networks are encapsulated into droplets surrounded by a lipid monolayer membrane. We find that the droplet can move when the actomyosin networks are bound to the membrane, in which the physical interaction between the contracting actomyosin networks and the membrane generates a propulsive force. The droplet moves faster when it has a larger contact area with the substrates, while narrower confinement reduces the migration speed. By combining experimental observations and active gel theory, we propose a mechanism where the balance between sliding friction force, which is a reaction force of the contractile force, and viscous drag determines the migration speed, providing a physical basis of actomyosin-based motility in confined environments.
Collapse
|
8
|
Moud AA. Fluorescence Recovery after Photobleaching in Colloidal Science: Introduction and Application. ACS Biomater Sci Eng 2022; 8:1028-1048. [PMID: 35201752 DOI: 10.1021/acsbiomaterials.1c01422] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
FRAP (fluorescence recovery after photo bleaching) is a method for determining diffusion in material science. In industrial applications such as medications, foods, Medtech, hygiene, and textiles, the diffusion process has a substantial influence on the overall qualities of goods. All these complex and heterogeneous systems have diffusion-based processes at the local level. FRAP is a fluorescence-based approach for detecting diffusion; in this method, a high-intensity laser is made for a brief period and then applied to the samples, bleaching the fluorescent chemical inside the region, which is subsequently filled up by natural diffusion. This brief Review will focus on the existing research on employing FRAP to measure colloidal system heterogeneity and explore diffusion into complicated structures. This description of FRAP will be followed by a discussion of how FRAP is intended to be used in colloidal science. When constructing the current Review, the most recent publications were reviewed for this assessment. Because of the large number of FRAP articles in colloidal research, there is currently a dearth of knowledge regarding the growth of FRAP's significance to colloidal science. Colloids make up only 2% of FRAP papers, according to ISI Web of Knowledge.
Collapse
Affiliation(s)
- Aref Abbasi Moud
- Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| |
Collapse
|
9
|
Abstract
Accurate decoding of spatial chemical landscapes is critical for many cell functions. Eukaryotic cells decode local chemical gradients to orient growth or movement in productive directions. Recent work on yeast model systems, whose gradient sensing pathways display much less complexity than those in animal cells, has suggested new paradigms for how these very small cells successfully exploit information in noisy and dynamic pheromone gradients to identify their mates. Pheromone receptors regulate a polarity circuit centered on the conserved Rho-family GTPase, Cdc42. The polarity circuit contains both positive and negative feedback pathways, allowing spontaneous symmetry breaking and also polarity site disassembly and relocation. Cdc42 orients the actin cytoskeleton, leading to focused vesicle traffic that promotes movement of the polarity site and also reshapes the cortical distribution of receptors at the cell surface. In this article, we review the advances from work on yeasts and compare them with the excitable signaling pathways that have been revealed in chemotactic animal cells. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Collapse
Affiliation(s)
- Debraj Ghose
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA;
| | - Timothy Elston
- Department of Pharmacology, University of North Carolina at Chapel Hill, North Carolina, USA
| | - Daniel Lew
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA;
| |
Collapse
|
10
|
Abstract
The eukaryotic cell's cytoskeleton is a prototypical example of an active material: objects embedded within it are driven by molecular motors acting on the cytoskeleton, leading to anomalous diffusive behavior. Experiments tracking the behavior of cell-attached objects have observed anomalous diffusion with a distribution of displacements that is non-Gaussian, with heavy tails. This has been attributed to "cytoquakes" or other spatially extended collective effects. We show, using simulations and analytical theory, that a simple continuum active gel model driven by fluctuating force dipoles naturally creates heavy power-law tails in cytoskeletal displacements. We predict that this power law exponent should depend on the geometry and dimensionality of where force dipoles are distributed through the cell; we find qualitatively different results for force dipoles in a 3D cytoskeleton and a quasi-two-dimensional cortex. We then discuss potential applications of this model both in cells and in synthetic active gels.
Collapse
Affiliation(s)
- Daniel W Swartz
- Department of Physics and Astronomy, Johns Hopkins University, USA
- Department of Physics, Massachusetts Institute of Technology, USA
| | - Brian A Camley
- Department of Physics and Astronomy, Johns Hopkins University, USA
- Department of Biophysics, Johns Hopkins University, USA
| |
Collapse
|
11
|
Marczynski M, Kimna C, Lieleg O. Purified mucins in drug delivery research. Adv Drug Deliv Rev 2021; 178:113845. [PMID: 34166760 DOI: 10.1016/j.addr.2021.113845] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/02/2021] [Accepted: 06/16/2021] [Indexed: 12/20/2022]
Abstract
One of the main challenges in the field of drug delivery remains the development of strategies to efficiently transport pharmaceuticals across mucus barriers, which regulate the passage and retention of molecules and particles in all luminal spaces of the body. A thorough understanding of the molecular mechanisms, which govern such selective permeability, is key for achieving efficient translocation of drugs and drug carriers. For this purpose, model systems based on purified mucins can contribute valuable information. In this review, we summarize advances that were made in the field of drug delivery research with such mucin-based model systems: First, we give an overview of mucin purification procedures and discuss the suitability of model systems reconstituted from purified mucins to mimic native mucus. Then, we summarize techniques to study mucin binding. Finally, we highlight approaches that made use of mucins as building blocks for drug delivery platforms or employ mucins as active compounds.
Collapse
|
12
|
Ierushalmi N, Keren K. Cytoskeletal symmetry breaking in animal cells. Curr Opin Cell Biol 2021; 72:91-99. [PMID: 34375786 DOI: 10.1016/j.ceb.2021.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/13/2021] [Accepted: 07/07/2021] [Indexed: 10/20/2022]
Abstract
Symmetry breaking is a crucial step in structure formation and function of all cells, necessary for cell movement, cell division, and polarity establishment. Although the mechanisms of symmetry breaking are diverse, they often share common characteristics. Here we review examples of nematic, polar, and chiral cytoskeletal symmetry breaking in animal cells, and analogous processes in simplified reconstituted systems. We discuss the origins of symmetry breaking, which can arise spontaneously, or involve amplification of a pre-existing external or internal bias to the whole cell level. The underlying mechanisms often involve both chemical and mechanical processes that cooperate to break symmetry in a robust manner, and typically depend on the shape, size, or properties of the cell's boundary.
Collapse
Affiliation(s)
- Niv Ierushalmi
- Department of Physics, Technion - Israel Institute of Technology, Haifa, Israel
| | - Kinneret Keren
- Department of Physics, Technion - Israel Institute of Technology, Haifa, Israel; Network Biology Research Laboratories and Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa, Israel.
| |
Collapse
|
13
|
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.
Collapse
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
| |
Collapse
|
14
|
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.
Collapse
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.
| |
Collapse
|
15
|
Bleicher P, Nast-Kolb T, Sciortino A, de la Trobe YA, Pokrant T, Faix J, Bausch AR. Intra-bundle contractions enable extensile properties of active actin networks. Sci Rep 2021; 11:2677. [PMID: 33514794 PMCID: PMC7846802 DOI: 10.1038/s41598-021-81601-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 01/05/2021] [Indexed: 12/27/2022] Open
Abstract
The cellular cortex is a dynamic and contractile actomyosin network modulated by actin-binding proteins. We reconstituted a minimal cortex adhered to a model cell membrane mimicking two processes mediated by the motor protein myosin: contractility and high turnover of actin monomers. Myosin reorganized these networks by extensile intra‑bundle contractions leading to an altered growth mechanism. Hereby, stress within tethered bundles induced nicking of filaments followed by repair via incorporation of free monomers. This mechanism was able to break the symmetry of the previously disordered network resulting in the generation of extensile clusters, reminiscent of structures found within cells.
Collapse
Affiliation(s)
- P Bleicher
- Physik-Department, Lehrstuhl für Biophysik E27, Technische Universität München, Garching, Germany. .,Center for Protein Assemblies (CPA), Ernst-Otto-Fischer Str. 8, 85747, Garching, Germany.
| | - T Nast-Kolb
- Physik-Department, Lehrstuhl für Biophysik E27, Technische Universität München, Garching, Germany.,Center for Protein Assemblies (CPA), Ernst-Otto-Fischer Str. 8, 85747, Garching, Germany
| | - A Sciortino
- Physik-Department, Lehrstuhl für Biophysik E27, Technische Universität München, Garching, Germany.,Center for Protein Assemblies (CPA), Ernst-Otto-Fischer Str. 8, 85747, Garching, Germany
| | - Y A de la Trobe
- Physik-Department, Lehrstuhl für Biophysik E27, Technische Universität München, Garching, Germany.,Center for Protein Assemblies (CPA), Ernst-Otto-Fischer Str. 8, 85747, Garching, Germany
| | - T Pokrant
- Institut für Biophysikalische Chemie, Medizinische Hochschule Hannover, Hannover, Germany
| | - J Faix
- Institut für Biophysikalische Chemie, Medizinische Hochschule Hannover, Hannover, Germany
| | - A R Bausch
- Physik-Department, Lehrstuhl für Biophysik E27, Technische Universität München, Garching, Germany. .,Center for Protein Assemblies (CPA), Ernst-Otto-Fischer Str. 8, 85747, Garching, Germany.
| |
Collapse
|
16
|
The Actomyosin Cortex of Cells: A Thin Film of Active Matter. J Indian Inst Sci 2021. [DOI: 10.1007/s41745-020-00220-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
17
|
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.
Collapse
|
18
|
Johnston CA. A Cell Adhesion-Based Reconstitution Method for Studying Cell Polarity. Front Cell Dev Biol 2020; 8:598492. [PMID: 33195282 PMCID: PMC7649242 DOI: 10.3389/fcell.2020.598492] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 10/07/2020] [Indexed: 11/24/2022] Open
Abstract
Cell polarity is an evolutionarily conserved process of asymmetric spatial organization within cells and is essential to tissue structure, signal transduction, cell migration, and cell division. The establishment and maintenance of polarity typically involves extensive protein-protein interactions that can be made further intricate by cell cycle-dependent regulation. These aspects can make interpreting phenotypes within traditional in vivo genetic systems challenging due to pleiotropic effects in loss-of-function experiments. Minimal reconstitution methods offer investigators the advantage of stricter control of otherwise complex systems and allow for more direct assessment of the role of individual components to the process of interest. Here I provide a detailed protocol for a cell adhesion-based method of inducing cell polarity within non-polarized Drosophila S2 cells. This technique is simple, cost effective, moderate throughput, and amenable to RNAi-based loss-of-function studies. The ability to “plug-and-play” genes of interest allows investigators to easily assess the contribution of individual protein domains and post-translational modifications to their function. The system is ideally suited to test not only the requirement of individual components but also their sufficiency, and can provide important insight into the epistatic relationship among multiple components in a protein complex. Although designed for use within Drosophila cells, the general premise and protocol should be easily adapted to mammalian cell culture or other systems that may better suit the interests of potential users.
Collapse
|
19
|
Gires PY, Thampi M, Weiss M. Quantifying active diffusion in an agitated fluid. Phys Chem Chem Phys 2020; 22:21678-21684. [PMID: 32966453 DOI: 10.1039/d0cp03629c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Mixing of reactants in microdroplets predominantly relies on diffusional motion due to small Reynolds numbers and the resulting absence of turbulent flows. Enhancing diffusion in microdroplets by an auxiliary noise source is therefore a topical problem. Here we report on how the diffusional motion of tracer beads is enhanced upon agitating the surrounding aqueous fluid with miniaturized magnetic stir bars that are compatible with microdroplets and microfluidic devices. Using single-particle tracking, we demonstrate via a broad palette of measures that local stirring of the fluid at different frequencies leads to an enhanced but apparently normal and homogenous diffusion process, i.e. diffusional steps follow the anticipated Gaussian distribution and no ballistic motion is observed whereas diffusion coefficients are significantly increased. The signature of stirring is, however, visible in the power-spectral density and in the velocity autocorrelation function of trajectories. Our data therefore demonstrate that diffusive mixing can be locally enhanced with miniaturized stir bars while only moderately affecting the ambient noise properties. The latter may also facilitate the controlled addition of nonequilibrium noise to complex fluids in future applications.
Collapse
Affiliation(s)
- Pierre-Yves Gires
- Experimental Physics I, University of Bayreuth, Universitätsstr. 30, D-95447 Bayreuth, Germany.
| | - Mithun Thampi
- Experimental Physics I, University of Bayreuth, Universitätsstr. 30, D-95447 Bayreuth, Germany.
| | - Matthias Weiss
- Experimental Physics I, University of Bayreuth, Universitätsstr. 30, D-95447 Bayreuth, Germany.
| |
Collapse
|
20
|
Jahnke K, Weiss M, Weber C, Platzman I, Göpfrich K, Spatz JP. Engineering Light-Responsive Contractile Actomyosin Networks with DNA Nanotechnology. ACTA ACUST UNITED AC 2020; 4:e2000102. [PMID: 32696544 DOI: 10.1002/adbi.202000102] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 06/26/2020] [Accepted: 06/30/2020] [Indexed: 01/01/2023]
Abstract
External control and precise manipulation is key for the bottom-up engineering of complex synthetic cells. Minimal actomyosin networks have been reconstituted into synthetic cells; however, their light-triggered symmetry breaking contraction has not yet been demonstrated. Here, light-activated directional contractility of a minimal synthetic actomyosin network inside microfluidic cell-sized compartments is engineered. Actin filaments, heavy-meromyosin-coated beads, and caged ATP are co-encapsulated into water-in-oil droplets. ATP is released upon illumination, leading to a myosin-generated force which results in a motion of the beads along the filaments and hence a contraction of the network. Symmetry breaking is achieved using DNA nanotechnology to establish a link between the network and the compartment periphery. It is demonstrated that the DNA-linked actin filaments contract to one side of the compartment forming actin asters and quantify the dynamics of this process. This work exemplifies that an engineering approach to bottom-up synthetic biology, combining biological and artificial elements, can circumvent challenges related to active multi-component systems and thereby greatly enrich the complexity of synthetic cellular systems.
Collapse
Affiliation(s)
- Kevin Jahnke
- Biophysical Engineering Group, Max Planck Institute for Medical Research, Jahnstraße 29, Heidelberg, D 69120, Germany.,Department of Physics and Astronomy, Heidelberg University, Heidelberg, D 69120, Germany
| | - Marian Weiss
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, Heidelberg, D 69120, Germany.,Institute for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld, Heidelberg, D 69120, Germany
| | - Cornelia Weber
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, Heidelberg, D 69120, Germany.,Institute for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld, Heidelberg, D 69120, Germany
| | - Ilia Platzman
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, Heidelberg, D 69120, Germany.,Institute for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld, Heidelberg, D 69120, Germany
| | - Kerstin Göpfrich
- Biophysical Engineering Group, Max Planck Institute for Medical Research, Jahnstraße 29, Heidelberg, D 69120, Germany.,Department of Physics and Astronomy, Heidelberg University, Heidelberg, D 69120, Germany
| | - Joachim P Spatz
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, Heidelberg, D 69120, Germany.,Institute for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld, Heidelberg, D 69120, Germany.,Max Planck School Matter to Life, Jahnstraße 29, Heidelberg, D 69120, Germany
| |
Collapse
|
21
|
Tug-of-war between actomyosin-driven antagonistic forces determines the positioning symmetry in cell-sized confinement. Nat Commun 2020; 11:3063. [PMID: 32541780 PMCID: PMC7295813 DOI: 10.1038/s41467-020-16677-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 05/06/2020] [Indexed: 12/18/2022] Open
Abstract
Symmetric or asymmetric positioning of intracellular structures including the nucleus and mitotic spindle steers various biological processes such as cell migration, division, and embryogenesis. In typical animal cells, both a sparse actomyosin meshwork in the cytoplasm and a dense actomyosin cortex underneath the cell membrane participate in the intracellular positioning. However, it remains unclear how these coexisting actomyosin structures regulate the positioning symmetry. To reveal the potential mechanism, we construct an in vitro model composed of cytoplasmic extracts and nucleus-like clusters confined in droplets. Here we find that periodic centripetal actomyosin waves contract from the droplet boundary push clusters to the center in large droplets, while network percolation of bulk actomyosin pulls clusters to the edge in small droplets. An active gel model quantitatively reproduces molecular perturbation experiments, which reveals that the tug-of-war between two distinct actomyosin networks with different maturation time-scales determines the positioning symmetry.
Collapse
|
22
|
Abstract
The cell-free molecular synthesis of biochemical systems is a rapidly growing field of research. Advances in the Human Genome Project, DNA synthesis, and other technologies have allowed the in vitro construction of biochemical systems, termed cell-free biology, to emerge as an exciting domain of bioengineering. Cell-free biology ranges from the molecular to the cell-population scales, using an ever-expanding variety of experimental platforms and toolboxes. In this review, we discuss the ongoing efforts undertaken in the three major classes of cell-free biology methodologies, namely protein-based, nucleic acids–based, and cell-free transcription–translation systems, and provide our perspectives on the current challenges as well as the major goals in each of the subfields.
Collapse
Affiliation(s)
- Vincent Noireaux
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Allen P. Liu
- Departments of Mechanical Engineering, Biomedical Engineering, Biophysics, and the Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan 48109, USA
| |
Collapse
|
23
|
Trinschek S, Stegemerten F, John K, Thiele U. Thin-film modeling of resting and moving active droplets. Phys Rev E 2020; 101:062802. [PMID: 32688574 DOI: 10.1103/physreve.101.062802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 04/21/2020] [Indexed: 06/11/2023]
Abstract
We propose a generic model for thin films and shallow drops of a polar active liquid that have a free surface and are in contact with a solid substrate. The model couples evolution equations for the film height and the local polarization in the form of a gradient dynamics supplemented with active stresses and fluxes. A wetting energy for a partially wetting liquid is incorporated allowing for motion of the liquid-solid-gas contact line. This gives a consistent basis for the description of drops of dense bacterial suspensions or compact aggregates of living cells on solid substrates. As example, we analyze the dynamics of two-dimensional active drops (i.e., ridges) and demonstrate how active forces compete with passive surface forces to shape droplets and drive their motion. In our simple two-dimensional scenario we find that defect structures within the polarization profile drastically influence the shape and motility of active droplets. Thus, we can observe a transition from resting to motile droplets via the elimination of defects in the polarization profile. Furthermore, droplet motility is modulated by strong active stresses. Contractile stresses even lead to topological changes, i.e., drop splitting, which is naturally encoded in the evolution equations.
Collapse
Affiliation(s)
- Sarah Trinschek
- Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 9, 48149 Münster, Germany
- Université Grenoble-Alpes, CNRS, Laboratoire Interdisciplinaire de Physique 38000 Grenoble, France
| | - Fenna Stegemerten
- Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 9, 48149 Münster, Germany
| | - Karin John
- Université Grenoble-Alpes, CNRS, Laboratoire Interdisciplinaire de Physique 38000 Grenoble, France
| | - Uwe Thiele
- Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 9, 48149 Münster, Germany
- Center for Nonlinear Science (CeNoS), Westfälische Wilhelms-Universität Münster, Corrensstrasse 2, 48149 Münster, Germany
| |
Collapse
|
24
|
Ierushalmi N, Malik-Garbi M, Manhart A, Abu Shah E, Goode BL, Mogilner A, Keren K. Centering and symmetry breaking in confined contracting actomyosin networks. eLife 2020; 9:55368. [PMID: 32314730 PMCID: PMC7173961 DOI: 10.7554/elife.55368] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 03/19/2020] [Indexed: 11/13/2022] Open
Abstract
Centering and decentering of cellular components is essential for internal organization of cells and their ability to perform basic cellular functions such as division and motility. How cells achieve proper localization of their organelles is still not well-understood, especially in large cells such as oocytes. Here, we study actin-based positioning mechanisms in artificial cells with persistently contracting actomyosin networks, generated by encapsulating cytoplasmic Xenopus egg extracts into cell-sized ‘water-in-oil’ droplets. We observe size-dependent localization of the contraction center, with a symmetric configuration in larger cells and a polar one in smaller cells. Centering is achieved via a hydrodynamic mechanism based on Darcy friction between the contracting network and the surrounding cytoplasm. During symmetry breaking, transient attachments to the cell boundary drive the contraction center to a polar location. The centering mechanism is cell-cycle dependent and weakens considerably during interphase. Our findings demonstrate a robust, yet tunable, mechanism for subcellular localization. In order to survive, cells need to react to their environment and change their shape or the localization of their internal components. For example, the nucleus – the compartment that contains the genetic information – is often localized at the center of the cell, but it can also be positioned at the side, for instance when cells move or divide asymmetrically. Cells use multiple positioning mechanisms to move their internal components, including a process that relies on networks of filaments made of a protein known as actin. These networks are constantly remodeled as actin proteins are added and removed from the network. Embedded molecular motors can cause the network of actin filaments to contract and push or pull on the compartments. Yet, the exact way these networks localize components in the cell remains unclear, especially in eggs and other large cells. To investigate this question, Ierushalmi et al. studied the actin networks in artificial cells that they created by enclosing the contents of frog eggs in small droplets surrounded by oil. This showed that the networks contracted either to the center of the cell or to its side. Friction between the contracting actin network and the fluid in the cell generated a force that tends to push the contraction center towards the middle of the cell. In larger cells, this led to the centering of the actin network. In smaller cells however, the network transiently attached to the boundary of the cell, leading the contraction center to be pulled to one side. By developing simpler artificial cells that mimic the positioning processes seen in real-life cells, Ierushalmi et al. discovered new mechanisms for how cells may center or de-center their components. This knowledge may be useful to understand diseases that can emerge when the nucleus or other compartments fail to move to the right location, and which are associated with certain organs developing incorrectly.
Collapse
Affiliation(s)
- Niv Ierushalmi
- Department of Physics, Technion- Israel Institute of Technology, Haifa, Israel
| | - Maya Malik-Garbi
- Department of Physics, Technion- Israel Institute of Technology, Haifa, Israel
| | - Angelika Manhart
- Department of Mathematics, University College London, London, United Kingdom
| | - Enas Abu Shah
- Department of Physics, Technion- Israel Institute of Technology, Haifa, Israel.,Kennedy Institute of Rheumatology, University of Oxford, Oxford, United Kingdom
| | - Bruce L Goode
- Department of Biology, Brandeis University, Waltham, United States
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences and Department of Biology, New York University, New York, United States
| | - Kinneret Keren
- Department of Physics, Technion- Israel Institute of Technology, Haifa, Israel.,Network Biology Research Laboratories and Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa, Israel
| |
Collapse
|
25
|
Dürre K, Bausch AR. Formation of phase separated vesicles by double layer cDICE. SOFT MATTER 2019; 15:9676-9681. [PMID: 31663090 DOI: 10.1039/c8sm02491j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Recently, continuous droplet interface crossing encapsulation (cDICE) was developed, which allows fast and efficient production of giant unilamellar vesicles (GUVs) under high salt conditions, at low temperature and with low consumption of the encapsulated proteins. Unfortunately, cholesterol encapsulation within the lipid bilayer was not efficient for the cDICE protocol so far and thus the formation of phase separated vesicles was limited. Here we present a modified version of cDICE that allows incorporation of cholesterol into lipid bilayers and enables the reproducible formation of phase-separated vesicles. We show that cholesterol incorporation relies on the amount of mineral oil in the lipid-oil emulsions, which is essential for protein encapsulation inside GUVs by cDICE. The possibility of creating phase separated vesicles by cDICE will enable the study of the interdependence between phase separation and cytoskeletal proteins under confinement.
Collapse
Affiliation(s)
- Katharina Dürre
- Lehrstuhl für Zellbiophysik E27, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany.
| | | |
Collapse
|
26
|
Senger F, Pitaval A, Ennomani H, Kurzawa L, Blanchoin L, Théry M. Spatial integration of mechanical forces by α-actinin establishes actin network symmetry. J Cell Sci 2019; 132:jcs.236604. [PMID: 31615968 DOI: 10.1242/jcs.236604] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 10/08/2019] [Indexed: 12/15/2022] Open
Abstract
Cell and tissue morphogenesis depend on the production and spatial organization of tensional forces in the actin cytoskeleton. Actin network architecture is made of distinct modules characterized by specific filament organizations. The assembly of these modules are well described, but their integration in a cellular network is less understood. Here, we investigated the mechanism regulating the interplay between network architecture and the geometry of the extracellular environment of the cell. We found that α-actinin, a filament crosslinker, is essential for network symmetry to be consistent with extracellular microenvironment symmetry. It is required for the interconnection of transverse arcs with radial fibres to ensure an appropriate balance between forces at cell adhesions and across the actin network. Furthermore, this connectivity appeared necessary for the ability of the cell to integrate and to adapt to complex patterns of extracellular cues as they migrate. Our study has unveiled a role of actin filament crosslinking in the spatial integration of mechanical forces that ensures the adaptation of intracellular symmetry axes in accordance with the geometry of extracellular cues.This article has an associated First Person interview with the first author of the paper.
Collapse
Affiliation(s)
- Fabrice Senger
- Université Grenoble-Alpes, CEA, CNRS, INRA, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorphoLab, 3800, Grenoble, France
| | - Amandine Pitaval
- Université Grenoble-Alpes, CEA, CNRS, INRA, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorphoLab, 3800, Grenoble, France.,Université Grenoble-Alpes, CEA, INRA, CNRS, UMR5168, Interdisciplinary Research Institute of Grenoble, Biomics Lab, 38000 Grenoble, France
| | - Hajer Ennomani
- Université Grenoble-Alpes, CEA, CNRS, INRA, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorphoLab, 3800, Grenoble, France
| | - Laetitia Kurzawa
- Université Grenoble-Alpes, CEA, CNRS, INRA, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorphoLab, 3800, Grenoble, France
| | - Laurent Blanchoin
- Université Grenoble-Alpes, CEA, CNRS, INRA, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorphoLab, 3800, Grenoble, France .,Université Paris Diderot, INSERM, CEA, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS 1160, CytoMorphoLab, 75010 Paris, France
| | - Manuel Théry
- Université Grenoble-Alpes, CEA, CNRS, INRA, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorphoLab, 3800, Grenoble, France .,Université Paris Diderot, INSERM, CEA, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS 1160, CytoMorphoLab, 75010 Paris, France
| |
Collapse
|
27
|
Mietke A, Jemseena V, Kumar KV, Sbalzarini IF, Jülicher F. Minimal Model of Cellular Symmetry Breaking. PHYSICAL REVIEW LETTERS 2019; 123:188101. [PMID: 31763902 DOI: 10.1103/physrevlett.123.188101] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Indexed: 06/10/2023]
Abstract
The cell cortex, a thin film of active material assembled below the cell membrane, plays a key role in cellular symmetry-breaking processes such as cell polarity establishment and cell division. Here, we present a minimal model of the self-organization of the cell cortex that is based on a hydrodynamic theory of curved active surfaces. Active stresses on this surface are regulated by a diffusing molecular species. We show that coupling of the active surface to a passive bulk fluid enables spontaneous polarization and the formation of a contractile ring on the surface via mechanochemical instabilities. We discuss the role of external fields in guiding such pattern formation. Our work reveals that key features of cellular symmetry breaking and cell division can emerge in a minimal model via general dynamic instabilities.
Collapse
Affiliation(s)
- Alexander Mietke
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
- Chair of Scientific Computing for Systems Biology, Faculty of Computer Science, TU Dresden, 01187 Dresden, Germany
- Center for Systems Biology Dresden, 01307 Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - V Jemseena
- International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, 560 089 Bengaluru, India
| | - K Vijay Kumar
- International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, 560 089 Bengaluru, India
| | - Ivo F Sbalzarini
- Chair of Scientific Computing for Systems Biology, Faculty of Computer Science, TU Dresden, 01187 Dresden, Germany
- Center for Systems Biology Dresden, 01307 Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Cluster of Excellence Physics of Life, TU Dresden, 01307 Dresden, Germany
| | - Frank Jülicher
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
- Center for Systems Biology Dresden, 01307 Dresden, Germany
- Cluster of Excellence Physics of Life, TU Dresden, 01307 Dresden, Germany
| |
Collapse
|
28
|
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.
Collapse
Affiliation(s)
- Yashar Bashirzadeh
- Department of Mechanical Engineering, University of Michigan, 2350 Hayward Street, Ann Arbor, Michigan, USA.
| | | |
Collapse
|
29
|
Gibeaux R, Heald R. The Use of Cell-Free Xenopus Extracts to Investigate Cytoplasmic Events. Cold Spring Harb Protoc 2019; 2019:pdb.top097048. [PMID: 29980587 DOI: 10.1101/pdb.top097048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Experiments using cytoplasmic extracts prepared from Xenopus eggs have made important contributions to our understanding of the cell cycle, the cytoskeleton, and cytoplasmic membrane systems. Here we introduce the extract system and describe methods for visualizing and manipulating diverse cytoplasmic processes, and for assaying the functions, dynamics, and stability of individual factors. These in vitro approaches uniquely enable investigation of events at specific cell cycle states, including the assembly of actin- and microtubule-based structures, and the formation of the endoplasmic reticulum. Maternal stockpiles in extracts recapitulate diverse processes in the near absence of gene expression, and this biochemical system combined with microscopy empowers a wide range of mechanistic investigations.
Collapse
Affiliation(s)
- Romain Gibeaux
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720-3200
| | - Rebecca Heald
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720-3200
| |
Collapse
|
30
|
Mierke CT. The matrix environmental and cell mechanical properties regulate cell migration and contribute to the invasive phenotype of cancer cells. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2019; 82:064602. [PMID: 30947151 DOI: 10.1088/1361-6633/ab1628] [Citation(s) in RCA: 122] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The minimal structural unit of a solid tumor is a single cell or a cellular compartment such as the nucleus. A closer look inside the cells reveals that there are functional compartments or even structural domains determining the overall properties of a cell such as the mechanical phenotype. The mechanical interaction of these living cells leads to the complex organization such as compartments, tissues and organs of organisms including mammals. In contrast to passive non-living materials, living cells actively respond to the mechanical perturbations occurring in their microenvironment during diseases such as fibrosis and cancer. The transformation of single cancer cells in highly aggressive and hence malignant cancer cells during malignant cancer progression encompasses the basement membrane crossing, the invasion of connective tissue, the stroma microenvironments and transbarrier migration, which all require the immediate interaction of the aggressive and invasive cancer cells with the surrounding extracellular matrix environment including normal embedded neighboring cells. All these steps of the metastatic pathway seem to involve mechanical interactions between cancer cells and their microenvironment. The pathology of cancer due to a broad heterogeneity of cancer types is still not fully understood. Hence it is necessary to reveal the signaling pathways such as mechanotransduction pathways that seem to be commonly involved in the development and establishment of the metastatic and mechanical phenotype in several carcinoma cells. We still do not know whether there exist distinct metastatic genes regulating the progression of tumors. These metastatic genes may then be activated either during the progression of cancer by themselves on their migration path or in earlier stages of oncogenesis through activated oncogenes or inactivated tumor suppressor genes, both of which promote the metastatic phenotype. In more detail, the adhesion of cancer cells to their surrounding stroma induces the generation of intracellular contraction forces that deform their microenvironments by alignment of fibers. The amplitude of these forces can adapt to the mechanical properties of the microenvironment. Moreover, the adhesion strength of cancer cells seems to determine whether a cancer cell is able to migrate through connective tissue or across barriers such as the basement membrane or endothelial cell linings of blood or lymph vessels in order to metastasize. In turn, exposure of adherent cancer cells to physical forces, such as shear flow in vessels or compression forces around tumors, reinforces cell adhesion, regulates cell contractility and restructures the ordering of the local stroma matrix that leads subsequently to secretion of crosslinking proteins or matrix degrading enzymes. Hence invasive cancer cells alter the mechanical properties of their microenvironment. From a mechanobiological point-of-view, the recognized physical signals are transduced into biochemical signaling events that guide cellular responses such as cancer progression after the malignant transition of cancer cells from an epithelial and non-motile phenotype to a mesenchymal and motile (invasive) phenotype providing cellular motility. This transition can also be described as the physical attempt to relate this cancer cell transitional behavior to a T1 phase transition such as the jamming to unjamming transition. During the invasion of cancer cells, cell adaptation occurs to mechanical alterations of the local stroma, such as enhanced stroma upon fibrosis, and therefore we need to uncover underlying mechano-coupling and mechano-regulating functional processes that reinforce the invasion of cancer cells. Moreover, these mechanisms may also be responsible for the awakening of dormant residual cancer cells within the microenvironment. Physicists were initially tempted to consider the steps of the cancer metastasis cascade as single events caused by a single mechanical alteration of the overall properties of the cancer cell. However, this general and simple view has been challenged by the finding that several mechanical properties of cancer cells and their microenvironment influence each other and continuously contribute to tumor growth and cancer progression. In addition, basement membrane crossing, cell invasion and transbarrier migration during cancer progression is explained in physical terms by applying physical principles on living cells regardless of their complexity and individual differences of cancer types. As a novel approach, the impact of the individual microenvironment surrounding cancer cells is also included. Moreover, new theories and models are still needed to understand why certain cancers are malignant and aggressive, while others stay still benign. However, due to the broad variety of cancer types, there may be various pathways solely suitable for specific cancer types and distinct steps in the process of cancer progression. In this review, physical concepts and hypotheses of cancer initiation and progression including cancer cell basement membrane crossing, invasion and transbarrier migration are presented and discussed from a biophysical point-of-view. In addition, the crosstalk between cancer cells and a chronically altered microenvironment, such as fibrosis, is discussed including the basic physical concepts of fibrosis and the cellular responses to mechanical stress caused by the mechanically altered microenvironment. Here, is highlighted how biophysical approaches, both experimentally and theoretically, have an impact on classical hallmarks of cancer and fibrosis and how they contribute to the understanding of the regulation of cancer and its progression by sensing and responding to the physical environmental properties through mechanotransduction processes. Finally, this review discusses various physical models of cell migration such as blebbing, nuclear piston, protrusive force and unjamming transition migration modes and how they contribute to cancer progression. Moreover, these cellular migration modes are influenced by microenvironmental perturbances such as fibrosis that can induce mechanical alterations in cancer cells, which in turn may impact the environment. Hence, the classical hallmarks of cancer need to be refined by including biomechanical properties of cells, cell clusters and tissues and their microenvironment to understand mechano-regulatory processes within cancer cells and the entire organism.
Collapse
|
31
|
Malik-Garbi M, Ierushalmi N, Jansen S, Abu-Shah E, Goode BL, Mogilner A, Keren K. Scaling behaviour in steady-state contracting actomyosin networks. NATURE PHYSICS 2019; 15:509-516. [PMID: 31754369 PMCID: PMC6871652 DOI: 10.1038/s41567-018-0413-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 12/20/2018] [Indexed: 05/25/2023]
Abstract
Contractile actomyosin network flows are crucial for many cellular processes including cell division and motility, morphogenesis and transport. How local remodeling of actin architecture tunes stress production and dissipation and regulates large-scale network flows remains poorly understood. Here, we generate contracting actomyosin networks with rapid turnover in vitro, by encapsulating cytoplasmic Xenopus egg extracts into cell-sized 'water-in-oil' droplets. Within minutes, the networks reach a dynamic steady-state with continuous inward flow. The networks exhibit homogeneous, density-independent contraction for a wide range of physiological conditions, implying that the myosin-generated stress driving contraction and the effective network viscosity have similar density dependence. We further find that the contraction rate is roughly proportional to the network turnover rate, but this relation breaks down in the presence of excessive crosslinking or branching. Our findings suggest that cells use diverse biochemical mechanisms to generate robust, yet tunable, actin flows by regulating two parameters: turnover rate and network geometry.
Collapse
Affiliation(s)
- Maya Malik-Garbi
- Department of Physics, Technion- Israel Institute of Technology, Haifa 32000, Israel
| | - Niv Ierushalmi
- Department of Physics, Technion- Israel Institute of Technology, Haifa 32000, Israel
| | - Silvia Jansen
- Department of Biology, Brandeis University, Waltham, MA, USA
- Department of Cell Biology and Physiology, Washington University St. Louis, St. Louis, MO, USA
| | - Enas Abu-Shah
- Department of Physics, Technion- Israel Institute of Technology, Haifa 32000, Israel
- Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, UK
| | - Bruce L Goode
- Department of Biology, Brandeis University, Waltham, MA, USA
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences and Department of Biology, New York University, New York, NY 10012, USA
| | - Kinneret Keren
- Department of Physics, Technion- Israel Institute of Technology, Haifa 32000, Israel
- Network Biology Research Laboratories and Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa 32000, Israel
| |
Collapse
|
32
|
|
33
|
Colin-York H, Li D, Korobchevskaya K, Chang VT, Betzig E, Eggeling C, Fritzsche M. Cytoskeletal actin patterns shape mast cell activation. Commun Biol 2019; 2:93. [PMID: 30854485 PMCID: PMC6405992 DOI: 10.1038/s42003-019-0322-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 01/22/2019] [Indexed: 01/05/2023] Open
Abstract
Activation of immune cells relies on a dynamic actin cytoskeleton. Despite detailed knowledge of molecular actin assembly, the exact processes governing actin organization during activation remain elusive. Using advanced microscopy, we here show that Rat Basophilic Leukemia (RBL) cells, a model mast cell line, employ an orchestrated series of reorganization events within the cortical actin network during activation. In response to IgE antigen-stimulation of FCε receptors (FCεR) at the RBL cell surface, we observed symmetry breaking of the F-actin network and subsequent rapid disassembly of the actin cortex. This was followed by a reassembly process that may be driven by the coordinated transformation of distinct nanoscale F-actin architectures, reminiscent of self-organizing actin patterns. Actin patterns co-localized with zones of Arp2/3 nucleation, while network reassembly was accompanied by myosin-II activity. Strikingly, cortical actin disassembly coincided with zones of granule secretion, suggesting that cytoskeletal actin patterns contribute to orchestrate RBL cell activation. Huw Colin-York et al. use advanced microscopy techniques to show that the cortical actin network within a model mast cell line undergoes a series of reorganizational events at the basal interface during activation. They find that actin patterns co-localize with zones of Arp2/3 nucleation and myosin-II activity accompanies network reassembly.
Collapse
Affiliation(s)
- Huw Colin-York
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford, OX3 9DS, UK
| | - Dong Li
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA, 20147, USA.,National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Kseniya Korobchevskaya
- Kennedy Institute for Rheumatology, University of Oxford, Roosevelt Drive, Oxford, OX3 7LF, UK
| | - Veronica T Chang
- MRC Laboratory of Molecular Biology, University of Cambridge, Cambridge, CB2 0QH, UK
| | - Eric Betzig
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA, 20147, USA
| | - Christian Eggeling
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford, OX3 9DS, UK
| | - Marco Fritzsche
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford, OX3 9DS, UK. .,Kennedy Institute for Rheumatology, University of Oxford, Roosevelt Drive, Oxford, OX3 7LF, UK.
| |
Collapse
|
34
|
Klinkert K, Levernier N, Gross P, Gentili C, von Tobel L, Pierron M, Busso C, Herrman S, Grill SW, Kruse K, Gönczy P. Aurora A depletion reveals centrosome-independent polarization mechanism in Caenorhabditis elegans. eLife 2019; 8:e44552. [PMID: 30801250 PMCID: PMC6417861 DOI: 10.7554/elife.44552] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 02/24/2019] [Indexed: 12/14/2022] Open
Abstract
How living systems break symmetry in an organized manner is a fundamental question in biology. In wild-type Caenorhabditis elegans zygotes, symmetry breaking during anterior-posterior axis specification is guided by centrosomes, resulting in anterior-directed cortical flows and a single posterior PAR-2 domain. We uncover that C. elegans zygotes depleted of the Aurora A kinase AIR-1 or lacking centrosomes entirely usually establish two posterior PAR-2 domains, one at each pole. We demonstrate that AIR-1 prevents symmetry breaking early in the cell cycle, whereas centrosomal AIR-1 instructs polarity initiation thereafter. Using triangular microfabricated chambers, we establish that bipolarity of air-1(RNAi) embryos occurs effectively in a cell-shape and curvature-dependent manner. Furthermore, we develop an integrated physical description of symmetry breaking, wherein local PAR-2-dependent weakening of the actin cortex, together with mutual inhibition of anterior and posterior PAR proteins, provides a mechanism for spontaneous symmetry breaking without centrosomes.
Collapse
Affiliation(s)
- Kerstin Klinkert
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL)LausanneSwitzerland
| | - Nicolas Levernier
- Department of BiochemistryUniversity of GenevaGenevaSwitzerland
- Department of Theoretical PhysicsUniversity of GenevaGenevaSwitzerland
| | | | - Christian Gentili
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL)LausanneSwitzerland
| | - Lukas von Tobel
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL)LausanneSwitzerland
| | - Marie Pierron
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL)LausanneSwitzerland
| | - Coralie Busso
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL)LausanneSwitzerland
| | - Sarah Herrman
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL)LausanneSwitzerland
| | - Stephan W Grill
- BIOTECTU DresdenDresdenGermany
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Cluster of Excellence Physics of LifeTU DresdenDresdenGermany
| | - Karsten Kruse
- Department of BiochemistryUniversity of GenevaGenevaSwitzerland
- Department of Theoretical PhysicsUniversity of GenevaGenevaSwitzerland
- National Center of Competence in Research Chemical Biology, University of GenevaGenevaSwitzerland
| | - Pierre Gönczy
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL)LausanneSwitzerland
| |
Collapse
|
35
|
Ganzinger KA, Schwille P. More from less - bottom-up reconstitution of cell biology. J Cell Sci 2019; 132:132/4/jcs227488. [PMID: 30718262 DOI: 10.1242/jcs.227488] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The ultimate goal of bottom-up synthetic biology is recreating life in its simplest form. However, in its quest to find the minimal functional units of life, this field contributes more than its main aim by also offering a range of tools for asking, and experimentally approaching, biological questions. This Review focusses on how bottom-up reconstitution has furthered our understanding of cell biology. Studying cell biological processes in vitro has a long tradition, but only recent technological advances have enabled researchers to reconstitute increasingly complex biomolecular systems by controlling their multi-component composition and their spatiotemporal arrangements. We illustrate this progress using the example of cytoskeletal processes. Our understanding of these has been greatly enhanced by reconstitution experiments, from the first in vitro experiments 70 years ago to recent work on minimal cytoskeleton systems (including this Special Issue of Journal of Cell Science). Importantly, reconstitution approaches are not limited to the cytoskeleton field. Thus, we also discuss progress in other areas, such as the shaping of biomembranes and cellular signalling, and prompt the reader to add their subfield of cell biology to this list in the future.
Collapse
Affiliation(s)
- Kristina A Ganzinger
- Physics of Cellular Interactions Group, AMOLF, 1098 XG Amsterdam, The Netherlands
| | - Petra Schwille
- Department Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| |
Collapse
|
36
|
Colin A, Singaravelu P, Théry M, Blanchoin L, Gueroui Z. Actin-Network Architecture Regulates Microtubule Dynamics. Curr Biol 2018; 28:2647-2656.e4. [PMID: 30100343 DOI: 10.1016/j.cub.2018.06.028] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 03/13/2018] [Accepted: 06/14/2018] [Indexed: 11/25/2022]
Abstract
Coordination between actin filaments and microtubules is critical to complete important steps during cell division. For instance, cytoplasmic actin filament dynamics play an active role in the off-center positioning of the spindle during metaphase I in mouse oocytes [1-3] or in gathering the chromosomes to ensure proper spindle formation in starfish oocytes [4, 5], whereas cortical actin filaments control spindle rotation and positioning in adherent cells or in mouse oocytes [6-9]. Several molecular effectors have been found to facilitate anchoring between the meiotic spindle and the cortical actin [10-14]. In vitro reconstitutions have provided detailed insights in the biochemical and physical interactions between microtubules and actin filaments [15-20]. Yet how actin meshwork architecture affects microtubule dynamics is still unclear. Here, we reconstituted microtubule aster in the presence of a meshwork of actin filaments using confined actin-intact Xenopus egg extracts. We found that actin filament branching reduces the lengths and growth rates of microtubules and constrains the mobility of microtubule asters. By reconstituting the interaction between dynamic actin filaments and microtubules in a minimal system based on purified proteins, we found that the branching of actin filaments is sufficient to block microtubule growth and trigger microtubule disassembly. In a further exploration of Xenopus egg extracts, we found that dense and static branched actin meshwork perturbs monopolar spindle assembly by constraining the motion of the spindle pole. Interestingly, monopolar spindle assembly was not constrained in conditions supporting dynamic meshwork rearrangements. We propose that branched actin filament meshwork provides physical barriers that limit microtubule growth.
Collapse
Affiliation(s)
- Alexandra Colin
- PASTEUR, Department of Chemistry, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Pavithra Singaravelu
- Université Grenoble-Alpes, CEA, CNRS, INRA, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, 17 rue des Martyrs, 38054 Grenoble, France
| | - Manuel Théry
- Université Grenoble-Alpes, CEA, CNRS, INRA, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, 17 rue des Martyrs, 38054 Grenoble, France; Université Paris Diderot, INSERM, CEA, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS1160, CytoMorpho Lab, 1 Avenue Claude Vellefaux, 75010 Paris, France
| | - Laurent Blanchoin
- Université Grenoble-Alpes, CEA, CNRS, INRA, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, 17 rue des Martyrs, 38054 Grenoble, France; Université Paris Diderot, INSERM, CEA, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS1160, CytoMorpho Lab, 1 Avenue Claude Vellefaux, 75010 Paris, France.
| | - Zoher Gueroui
- PASTEUR, Department of Chemistry, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.
| |
Collapse
|
37
|
Schön M, Mey I, Steinem C. Influence of cross-linkers on ezrin-bound minimal actin cortices. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 144:91-101. [PMID: 30093083 DOI: 10.1016/j.pbiomolbio.2018.07.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 07/13/2018] [Accepted: 07/31/2018] [Indexed: 12/21/2022]
Abstract
The actin cortex is a thin network coupled to the plasma membrane of cells, responsible for e.g., cell shape, motility, growth and division. Several model systems for minimal actin cortices (MACs) have been discussed in literature trying to mimic the complex interplay of membrane and actin. We recapitulate on different types of MACs using either three dimensional droplet interfaces or lipid bilayers to which F-actin networks are attached to or planar lipid bilayers with bound actin networks. Binding of the network to the membrane interface significantly influences its properties as well as its dynamics. This in turn also influences, how cross-linkers as well as myosin motors act on the network. Here, we describe the coupling of a filamentous actin network to a model membrane via the protein ezrin, a member of the ezrin-radixin-moesin family, which forms a direct linkage between the plasma membrane and the cortical web. Ezrin binding to the membrane is achieved by the lipid PtdIns(4,5)P2, while attachment to F-actin is mediated via the C-terminal domain of the protein leading to a two dimensional arrangement of actin filaments on the membrane. Addition of cross-linkers such as fascin and α-actinin influences the architecture of the actin network, which we have investigated by means of fluorescence microscopy. The results are discussed in terms of the dynamics of the filaments on the membrane surface.
Collapse
Affiliation(s)
- Markus Schön
- Georg-August Universität Göttingen, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany
| | - Ingo Mey
- Georg-August Universität Göttingen, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany.
| | - Claudia Steinem
- Georg-August Universität Göttingen, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany.
| |
Collapse
|
38
|
Miller PW, Stoop N, Dunkel J. Geometry of Wave Propagation on Active Deformable Surfaces. PHYSICAL REVIEW LETTERS 2018; 120:268001. [PMID: 30004728 DOI: 10.1103/physrevlett.120.268001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 03/05/2018] [Indexed: 06/08/2023]
Abstract
Fundamental biological and biomimetic processes, from tissue morphogenesis to soft robotics, rely on the propagation of chemical and mechanical surface waves to signal and coordinate active force generation. The complex interplay between surface geometry and contraction wave dynamics remains poorly understood, but it will be essential for the future design of chemically driven soft robots and active materials. Here, we couple prototypical chemical wave and reaction-diffusion models to non-Euclidean shell mechanics to identify and characterize generic features of chemomechanical wave propagation on active deformable surfaces. Our theoretical framework is validated against recent data from contractile wave measurements on ascidian and starfish oocytes, producing good quantitative agreement in both cases. The theory is then applied to illustrate how geometry and preexisting discrete symmetries can be utilized to focus active elastic surface waves. We highlight the practical potential of chemomechanical coupling by demonstrating spontaneous wave-induced locomotion of elastic shells of various geometries. Altogether, our results show how geometry, elasticity, and chemical signaling can be harnessed to construct dynamically adaptable, autonomously moving mechanical surface waveguides.
Collapse
Affiliation(s)
- Pearson W Miller
- Department of Mathematics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA
| | - Norbert Stoop
- Department of Mathematics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA
| | - Jörn Dunkel
- Department of Mathematics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA
| |
Collapse
|
39
|
Tan TH, Malik-Garbi M, Abu-Shah E, Li J, Sharma A, MacKintosh FC, Keren K, Schmidt CF, Fakhri N. Self-organized stress patterns drive state transitions in actin cortices. SCIENCE ADVANCES 2018; 4:eaar2847. [PMID: 29881775 PMCID: PMC5990313 DOI: 10.1126/sciadv.aar2847] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Accepted: 04/27/2018] [Indexed: 05/22/2023]
Abstract
Biological functions rely on ordered structures and intricately controlled collective dynamics. This order in living systems is typically established and sustained by continuous dissipation of energy. The emergence of collective patterns of motion is unique to nonequilibrium systems and is a manifestation of dynamic steady states. Mechanical resilience of animal cells is largely controlled by the actomyosin cortex. The cortex provides stability but is, at the same time, highly adaptable due to rapid turnover of its components. Dynamic functions involve regulated transitions between different steady states of the cortex. We find that model actomyosin cortices, constructed to maintain turnover, self-organize into distinct nonequilibrium steady states when we vary cross-link density. The feedback between actin network structure and organization of stress-generating myosin motors defines the symmetries of the dynamic steady states. A marginally cross-linked state displays divergence-free long-range flow patterns. Higher cross-link density causes structural symmetry breaking, resulting in a stationary converging flow pattern. We track the flow patterns in the model actomyosin cortices using fluorescent single-walled carbon nanotubes as novel probes. The self-organization of stress patterns we have observed in a model system can have direct implications for biological functions.
Collapse
Affiliation(s)
- Tzer Han Tan
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Maya Malik-Garbi
- Department of Physics, Technion—Israel Institute of Technology, Haifa, Israel
| | - Enas Abu-Shah
- Department of Physics, Technion—Israel Institute of Technology, Haifa, Israel
- Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa, Israel
| | - Junang Li
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Abhinav Sharma
- Department of Physics and Astronomy, Vrije Universiteit, Amsterdam, Netherlands
- Third Institute of Physics—Biophysics, University of Göttingen, Göttingen, Germany
| | - Fred C. MacKintosh
- Department of Physics and Astronomy, Vrije Universiteit, Amsterdam, Netherlands
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA
- Center for Theoretical Biophysics, Rice University, Houston, TX 77005, USA
| | - Kinneret Keren
- Department of Physics, Technion—Israel Institute of Technology, Haifa, Israel
- Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa, Israel
- Network Biology Research Laboratories, Technion—Israel Institute of Technology, Haifa, Israel
- Corresponding author. (K.K.); (C.F.S.); (N.F.)
| | - Christoph F. Schmidt
- Third Institute of Physics—Biophysics, University of Göttingen, Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), Göttingen, Germany
- Department of Physics, Duke University, Durham, NC 27708, USA
- Corresponding author. (K.K.); (C.F.S.); (N.F.)
| | - Nikta Fakhri
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Corresponding author. (K.K.); (C.F.S.); (N.F.)
| |
Collapse
|
40
|
Moreau HD, Piel M, Voituriez R, Lennon-Duménil AM. Integrating Physical and Molecular Insights on Immune Cell Migration. Trends Immunol 2018; 39:632-643. [PMID: 29779848 DOI: 10.1016/j.it.2018.04.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 04/18/2018] [Accepted: 04/18/2018] [Indexed: 01/09/2023]
Abstract
The function of most immune cells depends on their ability to migrate through complex microenvironments, either randomly to patrol for the presence of antigens or directionally to reach their next site of action. The actin cytoskeleton and its partners are key conductors of immune cell migration as they control the intrinsic migratory properties of leukocytes as well as their capacity to respond to cues present in their environment. In this review we focus on the latest discoveries regarding the role of the actomyosin cytoskeleton in optimizing immune cell migration in complex environments, with a special focus on recent insights provided by physical modeling.
Collapse
Affiliation(s)
- Hélène D Moreau
- INSERM U932, Institut Curie, ANR-10-IDEX-0001-02 PSL* and ANR-11-LABX-0043, Paris, France.
| | - Matthieu Piel
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005 Paris, France; Institut Pierre-Gilles de Gennes, PSL Research University, F-75005 Paris, France
| | - Raphaël Voituriez
- Laboratoire Jean Perrin, UM 8237 CNRS/UPMC, 4 place Jussieu, 75005 Paris, France
| | | |
Collapse
|
41
|
Abstract
How do the cells in our body reconfigure their shape to achieve complex tasks like migration and mitosis, yet maintain their shape in response to forces exerted by, for instance, blood flow and muscle action? Cell shape control is defined by a delicate mechanical balance between active force generation and passive material properties of the plasma membrane and the cytoskeleton. The cytoskeleton forms a space-spanning fibrous network comprising three subsystems: actin, microtubules and intermediate filaments. Bottom-up reconstitution of minimal synthetic cells where these cytoskeletal subsystems are encapsulated inside a lipid vesicle provides a powerful avenue to dissect the force balance that governs cell shape control. Although encapsulation is technically demanding, a steady stream of advances in this technique has made the reconstitution of shape-changing minimal cells increasingly feasible. In this topical review we provide a route-map of the recent advances in cytoskeletal encapsulation techniques and outline recent reports that demonstrate shape change phenomena in simple biomimetic vesicle systems. We end with an outlook toward the next steps required to achieve more complex shape changes with the ultimate aim of building a fully functional synthetic cell with the capability to autonomously grow, divide and move.
Collapse
Affiliation(s)
- Yuval Mulla
- These authors contributed equally to this work
| | | | | |
Collapse
|
42
|
Capping protein-controlled actin polymerization shapes lipid membranes. Nat Commun 2018; 9:1630. [PMID: 29691404 PMCID: PMC5915599 DOI: 10.1038/s41467-018-03918-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 03/20/2018] [Indexed: 11/08/2022] Open
Abstract
Arp2/3 complex-mediated actin assembly at cell membranes drives the formation of protrusions or endocytic vesicles. To identify the mechanism by which different membrane deformations can be achieved, we reconstitute the basic membrane deformation modes of inward and outward bending in a confined geometry by encapsulating a minimal set of cytoskeletal proteins into giant unilamellar vesicles. Formation of membrane protrusions is favoured at low capping protein (CP) concentrations, whereas the formation of negatively bent domains is promoted at high CP concentrations. Addition of non-muscle myosin II results in full fission events in the vesicle system. The different deformation modes are rationalized by simulations of the underlying transient nature of the reaction kinetics. The relevance of the regulatory mechanism is supported by CP overexpression in mouse melanoma B16-F1 cells and therefore demonstrates the importance of the quantitative understanding of microscopic kinetic balances to address the diverse functionality of the cytoskeleton. Cell membrane protrusions and invaginations are both driven by actin assembly but the mechanism leading to different membrane shapes is unknown. Using a minimal system and modelling the authors reconstitute the deformation modes and identify capping protein as a regulator of both deformation types.
Collapse
|
43
|
Göpfrich K, Platzman I, Spatz JP. Mastering Complexity: Towards Bottom-up Construction of Multifunctional Eukaryotic Synthetic Cells. Trends Biotechnol 2018; 36:938-951. [PMID: 29685820 PMCID: PMC6100601 DOI: 10.1016/j.tibtech.2018.03.008] [Citation(s) in RCA: 156] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/22/2018] [Accepted: 03/23/2018] [Indexed: 12/11/2022]
Abstract
With the ultimate aim to construct a living cell, bottom-up synthetic biology strives to reconstitute cellular phenomena in vitro - disentangled from the complex environment of a cell. Recent work towards this ambitious goal has provided new insights into the mechanisms governing life. With the fast-growing library of functional modules for synthetic cells, their classification and integration become increasingly important. We discuss strategies to reverse-engineer and recombine functional parts for synthetic eukaryotes, mimicking the characteristics of nature's own prototype. Particularly, we focus on large outer compartments, complex endomembrane systems with organelles, and versatile cytoskeletons as hallmarks of eukaryotic life. Moreover, we identify microfluidics and DNA nanotechnology as two technologies that can integrate these functional modules into sophisticated multifunctional synthetic cells.
Collapse
Affiliation(s)
- Kerstin Göpfrich
- Max Planck Institute for Medical Research, Department of Cellular Biophysics, Jahnstraße 29, D 69120, Heidelberg, Germany; Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, D 69120 Heidelberg, Germany.
| | - Ilia Platzman
- Max Planck Institute for Medical Research, Department of Cellular Biophysics, Jahnstraße 29, D 69120, Heidelberg, Germany; Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, D 69120 Heidelberg, Germany.
| | - Joachim P Spatz
- Max Planck Institute for Medical Research, Department of Cellular Biophysics, Jahnstraße 29, D 69120, Heidelberg, Germany; Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, D 69120 Heidelberg, Germany.
| |
Collapse
|
44
|
Architecture shapes contractility in actomyosin networks. Curr Opin Cell Biol 2018; 50:79-85. [PMID: 29482169 DOI: 10.1016/j.ceb.2018.01.015] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 01/30/2018] [Indexed: 01/03/2023]
Abstract
Myosin-driven contraction of the actin cytoskeleton is at the base of cell and tissue morphogenesis. At the molecular level, myosin motors drive contraction by sliding actin filaments past one another using energy produced by ATP hydrolysis. How this microscopic sliding activity gives rise to cell-scale contractions has been an active research question first in muscle cells, and over the last few decades in non-muscle cells. While many early investigations focused on myosin motor activity, increasingly, the nanoscale architecture of the actin network emerges as a key regulator of contractility. Here we review theoretical and in vitro reconstitution studies that have uncovered some of the key mechanisms by which actin network organization controls contractile tension generation. We then discuss recent findings indicating that similar principles apply in cells.
Collapse
|
45
|
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.
Collapse
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
| |
Collapse
|
46
|
Belmonte JM, Leptin M, Nédélec F. A theory that predicts behaviors of disordered cytoskeletal networks. Mol Syst Biol 2017; 13:941. [PMID: 28954810 PMCID: PMC5615920 DOI: 10.15252/msb.20177796] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 08/31/2017] [Accepted: 09/05/2017] [Indexed: 12/31/2022] Open
Abstract
Morphogenesis in animal tissues is largely driven by actomyosin networks, through tensions generated by an active contractile process. Although the network components and their properties are known, and networks can be reconstituted in vitro, the requirements for contractility are still poorly understood. Here, we describe a theory that predicts whether an isotropic network will contract, expand, or conserve its dimensions. This analytical theory correctly predicts the behavior of simulated networks, consisting of filaments with varying combinations of connectors, and reveals conditions under which networks of rigid filaments are either contractile or expansile. Our results suggest that pulsatility is an intrinsic behavior of contractile networks if the filaments are not stable but turn over. The theory offers a unifying framework to think about mechanisms of contractions or expansion. It provides the foundation for studying a broad range of processes involving cytoskeletal networks and a basis for designing synthetic networks.
Collapse
Affiliation(s)
- Julio M Belmonte
- Directors's Research/Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Maria Leptin
- Directors's Research/Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - François Nédélec
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| |
Collapse
|
47
|
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.
Collapse
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
| |
Collapse
|
48
|
Gross P, Kumar KV, Grill SW. How Active Mechanics and Regulatory Biochemistry Combine to Form Patterns in Development. Annu Rev Biophys 2017; 46:337-356. [DOI: 10.1146/annurev-biophys-070816-033602] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Peter Gross
- BIOTEC, Technische Universität Dresden, 01307 Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
| | - K. Vijay Kumar
- International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, Bengaluru 560089, India
| | - Stephan W. Grill
- BIOTEC, Technische Universität Dresden, 01307 Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
| |
Collapse
|
49
|
Lemière J, Valentino F, Campillo C, Sykes C. How cellular membrane properties are affected by the actin cytoskeleton. Biochimie 2016; 130:33-40. [PMID: 27693515 DOI: 10.1016/j.biochi.2016.09.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/26/2016] [Indexed: 11/30/2022]
Abstract
Lipid membranes define the boundaries of living cells and intracellular compartments. The dynamic remodelling of these membranes by the cytoskeleton, a very dynamic structure made of active biopolymers, is crucial in many biological processes such as motility or division. In this review, we present some aspects of cellular membranes and how they are affected by the presence of the actin cytoskeleton. We show that, in parallel with the direct study of membranes and cytoskeleton in vivo, biomimetic in vitro systems allow reconstitution of biological processes in a controlled environment. In particular, we show that liposomes, or giant unilamellar vesicles, encapsulating a reconstituted actin network polymerizing at their membrane are suitable models of living cells and can be used to decipher the relative contributions of membrane and actin on the mechanical properties of the cellular interface.
Collapse
Affiliation(s)
- J Lemière
- Department of Molecular Biophysics and Biochemistry, Nanobiology Institute, Yale University, New Haven, CT, USA.
| | - F Valentino
- Institut Curie, PSL Research University, CNRS, UMR 168, 75005, Paris, France; Sorbonne Universités, UPMC Univ Paris 06, 4 place Jussieu, 75005, Paris, France; Univ Paris Diderot, Sorbonne Paris Cité, 5 rue Thomas-Mann, 75205, Paris, France
| | - C Campillo
- Université Evry Val d'Essonne, LAMBE, Boulevard F Mitterrand, Evry, 91025, France
| | - C Sykes
- Institut Curie, PSL Research University, CNRS, UMR 168, 75005, Paris, France.
| |
Collapse
|
50
|
Ho KKY, Lee LM, Liu AP. Mechanically activated artificial cell by using microfluidics. Sci Rep 2016; 6:32912. [PMID: 27610921 PMCID: PMC5017192 DOI: 10.1038/srep32912] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 08/17/2016] [Indexed: 01/06/2023] Open
Abstract
All living organisms sense mechanical forces. Engineering mechanosensitive artificial cell through bottom-up in vitro reconstitution offers a way to understand how mixtures of macromolecules assemble and organize into a complex system that responds to forces. We use stable double emulsion droplets (aqueous/oil/aqueous) to prototype mechanosensitive artificial cells. In order to demonstrate mechanosensation in artificial cells, we develop a novel microfluidic device that is capable of trapping double emulsions into designated chambers, followed by compression and aspiration in a parallel manner. The microfluidic device is fabricated using multilayer soft lithography technology, and consists of a control layer and a deformable flow channel. Deflections of the PDMS membrane above the main microfluidic flow channels and trapping chamber array are independently regulated pneumatically by two sets of integrated microfluidic valves. We successfully compress and aspirate the double emulsions, which result in transient increase and permanent decrease in oil thickness, respectively. Finally, we demonstrate the influx of calcium ions as a response of our mechanically activated artificial cell through thinning of oil. The development of a microfluidic device to mechanically activate artificial cells creates new opportunities in force-activated synthetic biology.
Collapse
Affiliation(s)
- Kenneth K. Y. Ho
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Lap Man Lee
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Allen P. Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan, United States of America
- Biophysics Program, University of Michigan, Ann Arbor, Michigan, United States of America
| |
Collapse
|