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Mendová K, Otáhal M, Drab M, Daniel M. Size Matters: Rethinking Hertz Model Interpretation for Cell Mechanics Using AFM. Int J Mol Sci 2024; 25:7186. [PMID: 39000293 PMCID: PMC11241038 DOI: 10.3390/ijms25137186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 06/17/2024] [Accepted: 06/25/2024] [Indexed: 07/16/2024] Open
Abstract
Cell mechanics are a biophysical indicator of cell state, such as cancer metastasis, leukocyte activation, and cell cycle progression. Atomic force microscopy (AFM) is a widely used technique to measure cell mechanics, where the Young modulus of a cell is usually derived from the Hertz contact model. However, the Hertz model assumes that the cell is an elastic, isotropic, and homogeneous material and that the indentation is small compared to the cell size. These assumptions neglect the effects of the cytoskeleton, cell size and shape, and cell environment on cell deformation. In this study, we investigated the influence of cell size on the estimated Young's modulus using liposomes as cell models. Liposomes were prepared with different sizes and filled with phosphate buffered saline (PBS) or hyaluronic acid (HA) to mimic the cytoplasm. AFM was used to obtain the force indentation curves and fit them to the Hertz model. We found that the larger the liposome, the lower the estimated Young's modulus for both PBS-filled and HA-filled liposomes. This suggests that the Young modulus obtained from the Hertz model is not only a property of the cell material but also depends on the cell dimensions. Therefore, when comparing or interpreting cell mechanics using the Hertz model, it is essential to account for cell size.
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Affiliation(s)
- Katarína Mendová
- Department of Mechanics, Biomechanics and Mechatronics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technická 4, 16000 Prague, Czech Republic;
| | - Martin Otáhal
- Department of Natural Sciences, Faculty of Biomedical Engineering, Czech Technical University in Prague, Náměstí Sítná 3105, 27201 Kladno, Czech Republic;
| | - Mitja Drab
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, 1000 Ljubljana, Slovenia;
| | - Matej Daniel
- Department of Mechanics, Biomechanics and Mechatronics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technická 4, 16000 Prague, Czech Republic;
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2
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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.
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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
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3
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Tsai FC, Guérin G, Pernier J, Bassereau P. Actin-membrane linkers: Insights from synthetic reconstituted systems. Eur J Cell Biol 2024; 103:151402. [PMID: 38461706 DOI: 10.1016/j.ejcb.2024.151402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 02/10/2024] [Accepted: 02/28/2024] [Indexed: 03/12/2024] Open
Abstract
At the cell surface, the actin cytoskeleton and the plasma membrane interact reciprocally in a variety of processes related to the remodeling of the cell surface. The actin cytoskeleton has been known to modulate membrane organization and reshape the membrane. To this end, actin-membrane linking molecules play a major role in regulating actin assembly and spatially direct the interaction between the actin cytoskeleton and the membrane. While studies in cells have provided a wealth of knowledge on the molecular composition and interactions of the actin-membrane interface, the complex molecular interactions make it challenging to elucidate the precise actions of the actin-membrane linkers at the interface. Synthetic reconstituted systems, consisting of model membranes and purified proteins, have been a powerful approach to elucidate how actin-membrane linkers direct actin assembly to drive membrane shape changes. In this review, we will focus only on several actin-membrane linkers that have been studied by using reconstitution systems. We will discuss the design principles of these reconstitution systems and how they have contributed to the understanding of the cellular functions of actin-membrane linkers. Finally, we will provide a perspective on future research directions in understanding the intricate actin-membrane interaction.
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Affiliation(s)
- Feng-Ching Tsai
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR168, Physics of Cells and Cancer, Paris 75005, France.
| | - Gwendal Guérin
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR168, Physics of Cells and Cancer, Paris 75005, France
| | - Julien Pernier
- Tumor Cell Dynamics Unit, Inserm U1279, Gustave Roussy Institute, Université Paris-Saclay, Villejuif 94800, France
| | - Patricia Bassereau
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR168, Physics of Cells and Cancer, Paris 75005, France.
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4
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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.
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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
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5
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Maffeis V, Heuberger L, Nikoletić A, Schoenenberger C, Palivan CG. Synthetic Cells Revisited: Artificial Cells Construction Using Polymeric Building Blocks. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2305837. [PMID: 37984885 PMCID: PMC10885666 DOI: 10.1002/advs.202305837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 10/06/2023] [Indexed: 11/22/2023]
Abstract
The exponential growth of research on artificial cells and organelles underscores their potential as tools to advance the understanding of fundamental biological processes. The bottom-up construction from a variety of building blocks at the micro- and nanoscale, in combination with biomolecules is key to developing artificial cells. In this review, artificial cells are focused upon based on compartments where polymers are the main constituent of the assembly. Polymers are of particular interest due to their incredible chemical variety and the advantage of tuning the properties and functionality of their assemblies. First, the architectures of micro- and nanoscale polymer assemblies are introduced and then their usage as building blocks is elaborated upon. Different membrane-bound and membrane-less compartments and supramolecular structures and how they combine into advanced synthetic cells are presented. Then, the functional aspects are explored, addressing how artificial organelles in giant compartments mimic cellular processes. Finally, how artificial cells communicate with their surrounding and each other such as to adapt to an ever-changing environment and achieve collective behavior as a steppingstone toward artificial tissues, is taken a look at. Engineering artificial cells with highly controllable and programmable features open new avenues for the development of sophisticated multifunctional systems.
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Affiliation(s)
- Viviana Maffeis
- Department of ChemistryUniversity of BaselMattenstrasse 22BaselCH‐4002Switzerland
- NCCR‐Molecular Systems EngineeringBPR 1095, Mattenstrasse 24aBaselCH‐4058Switzerland
| | - Lukas Heuberger
- Department of ChemistryUniversity of BaselMattenstrasse 22BaselCH‐4002Switzerland
| | - Anamarija Nikoletić
- Department of ChemistryUniversity of BaselMattenstrasse 22BaselCH‐4002Switzerland
- Swiss Nanoscience InstituteUniversity of BaselKlingelbergstrasse 82BaselCH‐4056Switzerland
| | | | - Cornelia G. Palivan
- Department of ChemistryUniversity of BaselMattenstrasse 22BaselCH‐4002Switzerland
- NCCR‐Molecular Systems EngineeringBPR 1095, Mattenstrasse 24aBaselCH‐4058Switzerland
- Swiss Nanoscience InstituteUniversity of BaselKlingelbergstrasse 82BaselCH‐4056Switzerland
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6
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Kandiyoth FB, Michelot A. Reconstitution of actin-based cellular processes: Why encapsulation changes the rules. Eur J Cell Biol 2023; 102:151368. [PMID: 37922812 DOI: 10.1016/j.ejcb.2023.151368] [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: 07/05/2023] [Revised: 10/02/2023] [Accepted: 10/20/2023] [Indexed: 11/07/2023] Open
Abstract
While in vitro reconstitution of cellular processes is progressing rapidly, the encapsulation of biomimetic systems to reproduce the cellular environment is a major challenge. Here we review the difficulties, using reconstitution of processes dependent on actin polymerization as an example. Some of the problems are purely technical, due to the need for engineering strategies to encapsulate concentrated solutions in micrometer-sized compartments. However, other significant issues arise from the reduction of experimental volumes, which alters the chemical evolution of these non-equilibrium systems. Important parameters to consider for successful reconstitutions are the amount of each component, their consumption and renewal rates to guarantee their continuous availability.
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Affiliation(s)
| | - Alphée Michelot
- Aix Marseille Univ, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France.
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7
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Van de Cauter L, van Buren L, Koenderink GH, Ganzinger KA. Exploring Giant Unilamellar Vesicle Production for Artificial Cells - Current Challenges and Future Directions. SMALL METHODS 2023; 7:e2300416. [PMID: 37464561 DOI: 10.1002/smtd.202300416] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/30/2023] [Indexed: 07/20/2023]
Abstract
Creating an artificial cell from the bottom up is a long-standing challenge and, while significant progress has been made, the full realization of this goal remains elusive. Arguably, one of the biggest hurdles that researchers are facing now is the assembly of different modules of cell function inside a single container. Giant unilamellar vesicles (GUVs) have emerged as a suitable container with many methods available for their production. Well-studied swelling-based methods offer a wide range of lipid compositions but at the expense of limited encapsulation efficiency. Emulsion-based methods, on the other hand, excel at encapsulation but are only effective with a limited set of membrane compositions and may entrap residual additives in the lipid bilayer. Since the ultimate artificial cell will need to comply with both specific membrane and encapsulation requirements, there is still no one-method-fits-all solution for GUV formation available today. This review discusses the state of the art in different GUV production methods and their compatibility with GUV requirements and operational requirements such as reproducibility and ease of use. It concludes by identifying the most pressing issues and proposes potential avenues for future research to bring us one step closer to turning artificial cells into a reality.
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Affiliation(s)
- Lori Van de Cauter
- Autonomous Matter Department, AMOLF, Amsterdam, 1098 XG, The Netherlands
| | - Lennard van Buren
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, 2629 HZ, The Netherlands
| | - Gijsje H Koenderink
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, 2629 HZ, The Netherlands
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8
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Lopes Dos Santos R, Malo M, Campillo C. Spatial Control of Arp2/3-Induced Actin Polymerization on Phase-Separated Giant Unilamellar Vesicles. ACS Synth Biol 2023; 12:3267-3274. [PMID: 37909673 DOI: 10.1021/acssynbio.3c00268] [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] [Indexed: 11/03/2023]
Abstract
Deciphering the physical mechanisms underlying cell shape changes, while avoiding the cellular interior's complexity, involves the development of controlled basic biomimetic systems that imitate cell functions. In particular, the reconstruction of cytoskeletal dynamics on cell-sized giant unilamellar vesicles (GUVs) has allowed for the reconstituting of some cell-like processes in vitro. In fact, such a bottom-up strategy could be the basis for forming protocells able to reorganize or even move autonomously. However, reconstituting the subtle and controlled dynamics of the cytoskeleton-membrane interface in vitro remains an experimental challenge. Taking advantage of the lipid-induced segregation of an actin polymerization activator, we present a system that targets actin polymerization in specific domains of phase-separated GUVs. We observe actin networks localized on Lo, Ld, or on both types of domains and the actin-induced deformation or reorganization of these domains. These results suggest that the system we have developed here could pave the way for future experiments further detailing the interplay between actin dynamics and membrane heterogeneities.
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Affiliation(s)
- Rogério Lopes Dos Santos
- Université Paris-Saclay, Univ Evry, CY Cergy Paris Université, CNRS, LAMBE, 91025 Evry, Courcouronnes, France
| | - Michel Malo
- Université Paris-Saclay, Univ Evry, CY Cergy Paris Université, CNRS, LAMBE, 91025 Evry, Courcouronnes, France
| | - Clément Campillo
- Université Paris-Saclay, Univ Evry, CY Cergy Paris Université, CNRS, LAMBE, 91025 Evry, Courcouronnes, France
- Institut Universitaire de France (IUF), 75005 Paris, France
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9
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Razavi S, Wong F, Abubaker-Sharif B, Matsubayashi HT, Nakamura H, Sandoval E, Robinson DN, Chen B, Liu J, Iglesias PA, Inoue T. Synthetic control of actin polymerization and symmetry breaking in active protocells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.22.559060. [PMID: 37790449 PMCID: PMC10542490 DOI: 10.1101/2023.09.22.559060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Non-linear biomolecular interactions on the membranes drive membrane remodeling that underlies fundamental biological processes including chemotaxis, cytokinesis, and endocytosis. The multitude of biomolecules, the redundancy in their interactions, and the importance of spatiotemporal context in membrane organization hampers understanding the physical principles governing membrane mechanics. A minimal, in vitro system that models the functional interactions between molecular signaling and membrane remodeling, while remaining faithful to cellular physiology and geometry is powerful yet remains unachieved. Here, inspired by the biophysical processes underpinning chemotaxis, we reconstituted externally-controlled actin polymerization inside giant unilamellar vesicles, guiding self-organization on the membrane. We show that applying undirected external chemical inputs to this system results in directed actin polymerization and membrane deformation that are uncorrelated with upstream biochemical cues, indicating symmetry breaking. A biophysical model of the dynamics and mechanics of both actin polymerization and membrane shape suggests that inhomogeneous distributions of actin generate membrane shape deformations in a non-linear fashion, a prediction consistent with experimental measurements and subsequent local perturbations. The active protocellular system demonstrates the interplay between actin dynamics and membrane shape in a symmetry breaking context that is relevant to chemotaxis and a suite of other biological processes.
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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 & 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
| | - Eduardo Sandoval
- 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
| | - Jian Liu
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, 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
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