101
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Feng Y, Reinherz EL, Lang MJ. αβ T Cell Receptor Mechanosensing Forces out Serial Engagement. Trends Immunol 2018; 39:596-609. [PMID: 30060805 PMCID: PMC6154790 DOI: 10.1016/j.it.2018.05.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 05/15/2018] [Accepted: 05/31/2018] [Indexed: 11/08/2022]
Abstract
T lymphocytes use αβ T cell receptors (TCRs) to recognize
sparse antigenic peptides bound to MHC molecules (pMHCs) arrayed on
antigen-presenting cells (APCs). Contrary to conventional receptor–ligand
associations exemplified by antigen-antibody interactions, forces play a crucial
role in nonequilibrium mechanosensor-based T cell activation. Both T cell
motility and local cytoskeleton machinery exert forces (i.e., generate loads) on
TCR–pMHC bonds. We review biological features of the load-dependent
activation process as revealed by optical tweezers single molecule/single cell
and other biophysical measurements. The findings link pMHC-triggered TCRs to
single cytoskeletal motors; define the importance of energized anisotropic
(i.e., force direction dependent) activation; and characterize immunological
synapse formation as digital, revealing no serial requirement. The emerging
picture suggests new approaches for the monitoring and design of cytotoxic T
lymphocyte (CTL)-based immunotherapy.
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Affiliation(s)
- Yinnian Feng
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Ellis L Reinherz
- Laboratory of Immunobiology and Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
| | - Matthew J Lang
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37235, USA.
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102
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De R. A general model of focal adhesion orientation dynamics in response to static and cyclic stretch. Commun Biol 2018; 1:81. [PMID: 30271962 PMCID: PMC6123675 DOI: 10.1038/s42003-018-0084-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 06/03/2018] [Indexed: 12/11/2022] Open
Abstract
Understanding cellular response to mechanical forces is immensely important for a plethora of biological processes. Focal adhesions are multimolecular protein assemblies that connect the cell to the extracellular matrix and play a pivotal role in cell mechanosensing. Under time-varying stretches, focal adhesions dynamically reorganize and reorient and as a result, regulate the response of cells in tissues. Here I present a simple theoretical model based on, to my knowledge, a novel approach in the understanding of stretch-sensitive bond association and dissociation processes together with the elasticity of the cell-substrate system to predict the growth, stability, and the orientation of focal adhesions in the presence of static as well as cyclically varying stretches. The model agrees well with several experimental observations; most importantly, it explains the puzzling observations of parallel orientation of focal adhesions under static stretch and nearly perpendicular orientation in response to fast varying cyclic stretch. Rumi De presents a model for focal adhesion dynamics under static stretch and cyclic stretch conditions. The predictions agree with prior observations and may explain the puzzling observation that focal adhesions orient toward the parallel direction in the presence of static or quasi-static stretch, but toward the perpendicular direction under fast varying cyclic stretch.
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Affiliation(s)
- Rumi De
- Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, West Bengal, India.
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103
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Thoma J, Sapra KT, Müller DJ. Single-Molecule Force Spectroscopy of Transmembrane β-Barrel Proteins. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2018; 11:375-395. [PMID: 29894225 DOI: 10.1146/annurev-anchem-061417-010055] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Single-molecule force spectroscopy (SMFS) has been widely applied to study the mechanical unfolding and folding of transmembrane proteins. Here, we review the recent progress in characterizing bacterial and human transmembrane β-barrel proteins by SMFS. First, we describe the mechanical unfolding of transmembrane β-barrels, which follows a general mechanism dictated by the sequential unfolding and extraction of individual β-strands and β-hairpins from membranes. Upon force relaxation, the unfolded polypeptide can insert stepwise into the membrane as single β-strands or β-hairpins to fold as the native β-barrel. The refolding can be followed at a high spatial and temporal resolution, showing that small β-barrels are able to fold without assistance, whereas large and complex β-barrels require chaperone cofactors. Applied in the dynamic mode, SMFS can quantify the kinetic and mechanical properties of single β-hairpins and reveal complementary insight into the membrane protein structure and function relationship. We further outline the challenges that SMFS experiments must overcome for a comprehensive understanding of the folding and function of transmembrane β-barrel proteins.
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Affiliation(s)
- Johannes Thoma
- Department of Biosystems Science and Engineering, ETH Zürich, 4058 Basel, Switzerland;
| | | | - Daniel J Müller
- Department of Biosystems Science and Engineering, ETH Zürich, 4058 Basel, Switzerland;
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104
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de Rooij R, Kuhl E. Physical Biology of Axonal Damage. Front Cell Neurosci 2018; 12:144. [PMID: 29928193 PMCID: PMC5997835 DOI: 10.3389/fncel.2018.00144] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 05/09/2018] [Indexed: 11/29/2022] Open
Abstract
Excessive physical impacts to the head have direct implications on the structural integrity at the axonal level. Increasing evidence suggests that tau, an intrinsically disordered protein that stabilizes axonal microtubules, plays a critical role in the physical biology of axonal injury. However, the precise mechanisms of axonal damage remain incompletely understood. Here we propose a biophysical model of the axon to correlate the dynamic behavior of individual tau proteins under external physical forces to the evolution of axonal damage. To propagate damage across the scales, we adopt a consistent three-step strategy: First, we characterize the axonal response to external stretches and stretch rates for varying tau crosslink bond strengths using a discrete axonal damage model. Then, for each combination of stretch rates and bond strengths, we average the axonal force-stretch response of n = 10 discrete simulations, from which we derive and calibrate a homogenized constitutive model. Finally, we embed this homogenized model into a continuum axonal damage model of [1-d]-type in which d is a scalar damage parameter that is driven by the axonal stretch and stretch rate. We demonstrate that axonal damage emerges naturally from the interplay of physical forces and biological crosslinking. Our study reveals an emergent feature of the crosslink dynamics: With increasing loading rate, the axonal failure stretch increases, but axonal damage evolves earlier in time. For a wide range of physical stretch rates, from 0.1 to 10 /s, and biological bond strengths, from 1 to 100 pN, our model predicts a relatively narrow window of critical damage stretch thresholds, from 1.01 to 1.30, which agrees well with experimental observations. Our biophysical damage model can help explain the development and progression of axonal damage across the scales and will provide useful guidelines to identify critical damage level thresholds in response to excessive physical forces.
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Affiliation(s)
- Rijk de Rooij
- Department of Mechanical Engineering and Bioengineering, Stanford University, Stanford, CA, United States
| | - Ellen Kuhl
- Department of Mechanical Engineering and Bioengineering, Stanford University, Stanford, CA, United States
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105
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Kang H, Jung HJ, Wong DSH, Kim SK, Lin S, Chan KF, Zhang L, Li G, Dravid VP, Bian L. Remote Control of Heterodimeric Magnetic Nanoswitch Regulates the Adhesion and Differentiation of Stem Cells. J Am Chem Soc 2018; 140:5909-5913. [PMID: 29681155 DOI: 10.1021/jacs.8b03001] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Remote, noninvasive, and reversible control over the nanoscale presentation of bioactive ligands, such as Arg-Gly-Asp (RGD) peptide, is highly desirable for temporally regulating cellular functions in vivo. Herein, we present a novel strategy for physically uncaging RGD using a magnetic field that allows safe and deep tissue penetration. We developed a heterodimeric nanoswitch consisting of a magnetic nanocage (MNC) coupled to an underlying RGD-coated gold nanoparticle (AuNP) via a long flexible linker. Magnetically controlled movement of MNC relative to AuNP allowed reversible uncaging and caging of RGD that modulate physical accessibility of RGD for integrin binding, thereby regulating stem cell adhesion, both in vitro and in vivo. Reversible RGD uncaging by the magnetic nanoswitch allowed temporal regulation of stem cell adhesion, differentiation, and mechanosensing. This physical and reversible RGD uncaging utilizing heterodimeric magnetic nanoswitch is unprecedented and holds promise in the remote control of cellular behaviors in vivo.
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Affiliation(s)
- Heemin Kang
- Department of Biomedical Engineering , The Chinese University of Hong Kong , Hong Kong , China
| | - Hee Joon Jung
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
- International Institute for Nanotechnology , Evanston , Illinois 60208 , United States
- NUANCE Center , Northwestern University , Evanston , Illinois 60208 , United States
| | - Dexter Siu Hong Wong
- Department of Biomedical Engineering , The Chinese University of Hong Kong , Hong Kong , China
| | - Sung Kyu Kim
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
- International Institute for Nanotechnology , Evanston , Illinois 60208 , United States
- NUANCE Center , Northwestern University , Evanston , Illinois 60208 , United States
| | - Sien Lin
- Department of Orthopaedics & Traumatology, Faculty of Medicine , The Chinese University of Hong Kong , Prince of Wales Hospital, Shatin , Hong Kong , China
| | | | | | - Gang Li
- Department of Orthopaedics & Traumatology, Faculty of Medicine , The Chinese University of Hong Kong , Prince of Wales Hospital, Shatin , Hong Kong , China
| | - Vinayak P Dravid
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
- International Institute for Nanotechnology , Evanston , Illinois 60208 , United States
- NUANCE Center , Northwestern University , Evanston , Illinois 60208 , United States
| | - Liming Bian
- Department of Biomedical Engineering , The Chinese University of Hong Kong , Hong Kong , China
- Translational Research Centre of Regenerative Medicine and 3D Printing Technologies of Guangzhou Medical University , The Third Affiliated Hospital of Guangzhou Medical University , Guangzhou , Guangdong , China
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106
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Prystopiuk V, Feuillie C, Herman-Bausier P, Viela F, Alsteens D, Pietrocola G, Speziale P, Dufrêne YF. Mechanical Forces Guiding Staphylococcus aureus Cellular Invasion. ACS NANO 2018; 12:3609-3622. [PMID: 29633832 DOI: 10.1021/acsnano.8b00716] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Staphylococcus aureus can invade various types of mammalian cells, thereby enabling it to evade host immune defenses and antibiotics. The current model for cellular invasion involves the interaction between the bacterial cell surface located fibronectin (Fn)-binding proteins (FnBPA and FnBPB) and the α5β1 integrin in the host cell membrane. While it is believed that the extracellular matrix protein Fn serves as a bridging molecule between FnBPs and integrins, the fundamental forces involved are not known. Using single-cell and single-molecule experiments, we unravel the molecular forces guiding S. aureus cellular invasion, focusing on the prototypical three-component FnBPA-Fn-integrin interaction. We show that FnBPA mediates bacterial adhesion to soluble Fn via strong forces (∼1500 pN), consistent with a high-affinity tandem β-zipper, and that the FnBPA-Fn complex further binds to immobilized α5β1 integrins with a strength much higher than that of the classical Fn-integrin bond (∼100 pN). The high mechanical stability of the Fn bridge favors an invasion model in which Fn binding by FnBPA leads to the exposure of cryptic integrin-binding sites via allosteric activation, which in turn engage in a strong interaction with integrins. This activation mechanism emphasizes the importance of protein mechanobiology in regulating bacterial-host adhesion. We also find that Fn-dependent adhesion between S. aureus and endothelial cells strengthens with time, suggesting that internalization occurs within a few minutes. Collectively, our results provide a molecular foundation for the ability of FnBPA to trigger host cell invasion by S. aureus and offer promising prospects for the development of therapeutic approaches against intracellular pathogens.
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Affiliation(s)
- Valeria Prystopiuk
- Institute of Life Sciences , Université catholique de Louvain , Croix du Sud, 4-5, bte L7.07.06 , B-1348 Louvain-la-Neuve , Belgium
| | - Cécile Feuillie
- Institute of Life Sciences , Université catholique de Louvain , Croix du Sud, 4-5, bte L7.07.06 , B-1348 Louvain-la-Neuve , Belgium
| | - Philippe Herman-Bausier
- Institute of Life Sciences , Université catholique de Louvain , Croix du Sud, 4-5, bte L7.07.06 , B-1348 Louvain-la-Neuve , Belgium
| | - Felipe Viela
- Institute of Life Sciences , Université catholique de Louvain , Croix du Sud, 4-5, bte L7.07.06 , B-1348 Louvain-la-Neuve , Belgium
| | - David Alsteens
- Institute of Life Sciences , Université catholique de Louvain , Croix du Sud, 4-5, bte L7.07.06 , B-1348 Louvain-la-Neuve , Belgium
| | | | | | - Yves F Dufrêne
- Institute of Life Sciences , Université catholique de Louvain , Croix du Sud, 4-5, bte L7.07.06 , B-1348 Louvain-la-Neuve , Belgium
- Walloon Excellence in Life Sciences and Biotechnology (WELBIO) , 4000 Liège , Belgium
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107
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Enhancing Electrotransfection Efficiency through Improvement in Nuclear Entry of Plasmid DNA. MOLECULAR THERAPY. NUCLEIC ACIDS 2018; 11:263-271. [PMID: 29858061 PMCID: PMC5992438 DOI: 10.1016/j.omtn.2018.02.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 02/22/2018] [Accepted: 02/26/2018] [Indexed: 01/15/2023]
Abstract
The nuclear envelope is a physiological barrier to electrogene transfer. To understand different mechanisms of the nuclear entry for electrotransfected plasmid DNA (pDNA), the current study investigated how manipulation of the mechanisms could affect electrotransfection efficiency (eTE), transgene expression level (EL), and cell viability. In the investigation, cells were first synchronized at G2-M phase prior to electrotransfection so that the nuclear envelope breakdown (NEBD) occurred before pDNA entered the cells. The NEBD significantly increased the eTE and the EL while the cell viability was not compromised. In the second experiment, the cells were treated with a nuclear pore dilating agent (i.e., trans-1,2-cyclohexanediol). The treatment could increase the EL, but had only minor effects on eTE. Furthermore, the treatment was more cytotoxic, compared with the cell synchronization. In the third experiment, a nuclear targeting sequence (i.e., SV40) was incorporated into the pDNA prior to electrotransfection. The incorporation was more effective than the cell synchronization for enhancing the EL, but not the eTE, and the effectiveness was cell type dependent. Taken together, the data described above suggested that synchronization of the NEBD could be a practical approach to improving electrogene transfer in all dividing cells.
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108
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Delguste M, Koehler M, Alsteens D. Probing Single Virus Binding Sites on Living Mammalian Cells Using AFM. Methods Mol Biol 2018; 1814:483-514. [PMID: 29956251 DOI: 10.1007/978-1-4939-8591-3_29] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In the last years, atomic force microscopy (AFM)-based approaches have evolved into a powerful multiparametric tool that allows biological samples ranging from single receptors to membranes and tissues to be probed. Force-distance curve-based AFM (FD-based AFM) nowadays enables to image living cells at high resolution and simultaneously localize and characterize specific ligand-receptor binding events. In this chapter, we present how FD-based AFM permits to investigate virus binding to living mammalian cells and quantify the kinetic and thermodynamic parameters that describe the free-energy landscape of the single virus-receptor-mediated binding. Using a model virus, we probed the specific interaction with cells expressing its cognate receptor and measured the affinity of the interaction. Furthermore, we observed that the virus rapidly established specific multivalent interactions and found that each bond formed in sequence strengthens the attachment of the virus to the cell.
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Affiliation(s)
- Martin Delguste
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Melanie Koehler
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - David Alsteens
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
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109
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Gupta D, Grant DM, Zakir Hossain KM, Ahmed I, Sottile V. Role of geometrical cues in bone marrow-derived mesenchymal stem cell survival, growth and osteogenic differentiation. J Biomater Appl 2017; 32:906-919. [DOI: 10.1177/0885328217745699] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Dhanak Gupta
- Wolfson Centre for Stem Cells, Tissue Engineering and Modelling (STEM), School of Medicine, University of Nottingham, Nottingham, UK
- Advanced Materials Research Group, Faculty of Engineering, University of Nottingham, UK
| | - David M Grant
- Advanced Materials Research Group, Faculty of Engineering, University of Nottingham, UK
| | - Kazi M Zakir Hossain
- Advanced Materials Research Group, Faculty of Engineering, University of Nottingham, UK
| | - Ifty Ahmed
- Advanced Materials Research Group, Faculty of Engineering, University of Nottingham, UK
| | - Virginie Sottile
- Wolfson Centre for Stem Cells, Tissue Engineering and Modelling (STEM), School of Medicine, University of Nottingham, Nottingham, UK
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110
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Burgos-Bravo F, Figueroa NL, Casanova-Morales N, Quest AFG, Wilson CAM, Leyton L. Single-molecule measurements of the effect of force on Thy-1/αvβ3-integrin interaction using nonpurified proteins. Mol Biol Cell 2017; 29:326-338. [PMID: 29212879 PMCID: PMC5996956 DOI: 10.1091/mbc.e17-03-0133] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 10/10/2017] [Accepted: 12/01/2017] [Indexed: 12/11/2022] Open
Abstract
Single-molecule measurements combined with a novel mathematical strategy were applied to accurately characterize how bimolecular interactions respond to mechanical force, especially when protein purification is not possible. Specifically, we studied the effect of force on Thy-1/αvβ3 integrin interaction, a mediator of neuron-astrocyte communication. Thy-1 and αvβ3 integrin mediate bidirectional cell-to-cell communication between neurons and astrocytes. Thy-1/αvβ3 interactions stimulate astrocyte migration and the retraction of neuronal prolongations, both processes in which internal forces are generated affecting the bimolecular interactions that maintain cell–cell adhesion. Nonetheless, how the Thy-1/αvβ3 interactions respond to mechanical cues is an unresolved issue. In this study, optical tweezers were used as a single-molecule force transducer, and the Dudko-Hummer-Szabo model was applied to calculate the kinetic parameters of Thy-1/αvβ3 dissociation. A novel experimental strategy was implemented to analyze the interaction of Thy-1-Fc with nonpurified αvβ3-Fc integrin, whereby nonspecific rupture events were corrected by using a new mathematical approach. This methodology permitted accurately estimating specific rupture forces for Thy-1-Fc/αvβ3-Fc dissociation and calculating the kinetic and transition state parameters. Force exponentially accelerated Thy-1/αvβ3 dissociation, indicating slip bond behavior. Importantly, nonspecific interactions were detected even for purified proteins, highlighting the importance of correcting for such interactions. In conclusion, we describe a new strategy to characterize the response of bimolecular interactions to forces even in the presence of nonspecific binding events. By defining how force regulates Thy-1/αvβ3 integrin binding, we provide an initial step towards understanding how the neuron–astrocyte pair senses and responds to mechanical cues.
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Affiliation(s)
- Francesca Burgos-Bravo
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Studies of Exercise, Metabolism and Cancer, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile
| | - Nataniel L Figueroa
- Physics Department, Pontificia Universidad Católica de Chile, 782-0436 Santiago, Chile
| | - Nathalie Casanova-Morales
- Biochemistry and Molecular Biology Department, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, 838-0494 Santiago, Chile
| | - Andrew F G Quest
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Studies of Exercise, Metabolism and Cancer, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile
| | - Christian A M Wilson
- Biochemistry and Molecular Biology Department, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, 838-0494 Santiago, Chile
| | - Lisette Leyton
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile .,Advanced Center for Chronic Diseases (ACCDiS), Center for Studies of Exercise, Metabolism and Cancer, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile
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111
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Kang H, Wong DSH, Yan X, Jung HJ, Kim S, Lin S, Wei K, Li G, Dravid VP, Bian L. Remote Control of Multimodal Nanoscale Ligand Oscillations Regulates Stem Cell Adhesion and Differentiation. ACS NANO 2017; 11:9636-9649. [PMID: 28841292 DOI: 10.1021/acsnano.7b02857] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Cellular adhesion is regulated by the dynamic ligation process of surface receptors, such as integrin, to adhesive motifs, such as Arg-Gly-Asp (RGD). Remote control of adhesive ligand presentation using external stimuli is an appealing strategy for the temporal regulation of cell-implant interactions in vivo and was recently demonstrated using photochemical reaction. However, the limited tissue penetration of light potentially hampers the widespread applications of this method in vivo. Here, we present a strategy for modulating the nanoscale oscillations of an integrin ligand simply and solely by adjusting the frequency of an oscillating magnetic field to regulate the adhesion and differentiation of stem cells. A superparamagnetic iron oxide nanoparticle (SPION) was conjugated with the RGD ligand and anchored to a glass substrate by a long flexible poly(ethylene glycol) linker to allow the oscillatory motion of the ligand to be magnetically tuned. In situ magnetic scanning transmission electron microscopy and atomic force microscopy imaging confirmed the nanoscale motion of the substrate-tethered RGD-grafted SPION. Our findings show that ligand oscillations under a low oscillation frequency (0.1 Hz) of the magnetic field promoted integrin-ligand binding and the formation and maturation of focal adhesions and therefore the substrate adhesion of stem cells, while ligands oscillating under high frequency (2 Hz) inhibited integrin ligation and stem cell adhesion, both in vitro and in vivo. Temporal switching of the multimodal ligand oscillations between low- and high-frequency modes reversibly regulated stem cell adhesion. The ligand oscillations further induced the stem cell differentiation and mechanosensing in the same frequency-dependent manner. Our study demonstrates a noninvasive, penetrative, and tunable approach to regulate cellular responses to biomaterials in vivo. Our work not only provides additional insight into the design considerations of biomaterials to control cellular adhesion in vivo but also offers a platform to elucidate the fundamental understanding of the dynamic integrin-ligand binding that regulates the adhesion, differentiation, and mechanotransduction of stem cells.
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Affiliation(s)
| | | | | | - Hee Joon Jung
- International Institute for Nanotechnology , Evanston, Illinois 60208, United States
| | - Sungkyu Kim
- International Institute for Nanotechnology , Evanston, Illinois 60208, United States
| | | | | | | | - Vinayak P Dravid
- International Institute for Nanotechnology , Evanston, Illinois 60208, United States
| | - Liming Bian
- China Orthopedic Regenerative Medicine Group (CORMed) , Hangzhou 310000, China
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112
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Combining confocal and atomic force microscopy to quantify single-virus binding to mammalian cell surfaces. Nat Protoc 2017; 12:2275-2292. [PMID: 28981124 DOI: 10.1038/nprot.2017.112] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Over the past five years, atomic force microscopy (AFM)-based approaches have evolved into a powerful multiparametric tool set capable of imaging the surfaces of biological samples ranging from single receptors to membranes and tissues. One of these approaches, force-distance curve-based AFM (FD-based AFM), uses a probing tip functionalized with a ligand to image living cells at high-resolution and simultaneously localize and characterize specific ligand-receptor binding events. Analyzing data from FD-based AFM experiments using appropriate probabilistic models allows quantification of the kinetic and thermodynamic parameters that describe the free-energy landscape of the ligand-receptor bond. We have recently developed an FD-based AFM approach to quantify the binding events of single enveloped viruses to surface receptors of living animal cells while simultaneously observing them by fluorescence microscopy. This approach has provided insights into the early stages of the interaction between a virus and a cell. Applied to a model virus, we probed the specific interaction with cells expressing viral cognate receptors and measured the affinity of the interaction. Furthermore, we observed that the virus rapidly established specific multivalent interactions and found that each bond formed in sequence strengthened the attachment of the virus to the cell. Here we describe detailed procedures for probing the specific interactions of viruses with living cells; these procedures cover tip preparation, cell sample preparation, step-by-step FD-based AFM imaging and data analysis. Experienced microscopists should be able to master the entire set of protocols in 1 month.
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113
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Onesto V, Cancedda L, Coluccio ML, Nanni M, Pesce M, Malara N, Cesarelli M, Di Fabrizio E, Amato F, Gentile F. Nano-topography Enhances Communication in Neural Cells Networks. Sci Rep 2017; 7:9841. [PMID: 28851984 PMCID: PMC5575309 DOI: 10.1038/s41598-017-09741-w] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 07/28/2017] [Indexed: 12/31/2022] Open
Abstract
Neural cells are the smallest building blocks of the central and peripheral nervous systems. Information in neural networks and cell-substrate interactions have been heretofore studied separately. Understanding whether surface nano-topography can direct nerve cells assembly into computational efficient networks may provide new tools and criteria for tissue engineering and regenerative medicine. In this work, we used information theory approaches and functional multi calcium imaging (fMCI) techniques to examine how information flows in neural networks cultured on surfaces with controlled topography. We found that substrate roughness S a affects networks topology. In the low nano-meter range, S a = 0-30 nm, information increases with S a . Moreover, we found that energy density of a network of cells correlates to the topology of that network. This reinforces the view that information, energy and surface nano-topography are tightly inter-connected and should not be neglected when studying cell-cell interaction in neural tissue repair and regeneration.
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Affiliation(s)
- V Onesto
- Department of Experimental and Clinical Medicine, University of Magna Graecia, 88100, Catanzaro, Italy
| | - L Cancedda
- Istituto Italiano di Tecnologia, Via Morego 30, 16163, Genova, Italy
| | - M L Coluccio
- Department of Experimental and Clinical Medicine, University of Magna Graecia, 88100, Catanzaro, Italy
| | - M Nanni
- Istituto Italiano di Tecnologia, Via Morego 30, 16163, Genova, Italy
| | - M Pesce
- Istituto Italiano di Tecnologia, Via Morego 30, 16163, Genova, Italy
| | - N Malara
- Department of Experimental and Clinical Medicine, University of Magna Graecia, 88100, Catanzaro, Italy
| | - M Cesarelli
- Department of Electrical Engineering and Information Technology, University of Naples, 80125, Naples, Italy
| | - E Di Fabrizio
- Department of Experimental and Clinical Medicine, University of Magna Graecia, 88100, Catanzaro, Italy
- King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - F Amato
- Department of Experimental and Clinical Medicine, University of Magna Graecia, 88100, Catanzaro, Italy
| | - F Gentile
- Department of Electrical Engineering and Information Technology, University of Naples, 80125, Naples, Italy.
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Two Distinct Actin Networks Mediate Traction Oscillations to Confer Focal Adhesion Mechanosensing. Biophys J 2017; 112:780-794. [PMID: 28256237 PMCID: PMC5340160 DOI: 10.1016/j.bpj.2016.12.035] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 11/20/2016] [Accepted: 12/23/2016] [Indexed: 12/20/2022] Open
Abstract
Focal adhesions (FAs) are integrin-based transmembrane assemblies that connect a cell to its extracellular matrix (ECM). They are mechanosensors through which cells exert actin cytoskeleton-mediated traction forces to sense the ECM stiffness. Interestingly, FAs themselves are dynamic structures that adapt their growth in response to mechanical force. It is unclear how the cell manages the plasticity of the FA structure and the associated traction force to accurately sense ECM stiffness. Strikingly, FA traction forces oscillate in time and space, and govern the cell mechanosensing of ECM stiffness. However, precisely how and why the FA traction oscillates is unknown. We developed a model of FA growth that integrates the contributions of the branched actin network and stress fibers (SFs). Using the model in combination with experimental tests, we show that the retrograde flux of the branched actin network promotes the proximal growth of the FA and contributes to a traction peak near the FA’s distal tip. The resulting traction gradient within the growing FA favors SF formation near the FA’s proximal end. The SF-mediated actomyosin contractility further stabilizes the FA and generates a second traction peak near the center of the FA. Formin-mediated SF elongation negatively feeds back with actomyosin contractility, resulting in central traction peak oscillation. This underpins the observed FA traction oscillation and, importantly, broadens the ECM stiffness range over which FAs can accurately adapt to traction force generation. Actin cytoskeleton-mediated FA growth and maturation thus culminate with FA traction oscillation to drive efficient FA mechanosensing.
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116
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Nguyen NM, Angely C, Andre Dias S, Planus E, Filoche M, Pelle G, Louis B, Isabey D. Characterisation of cellular adhesion reinforcement by multiple bond force spectroscopy in alveolar epithelial cells. Biol Cell 2017; 109:255-272. [DOI: 10.1111/boc.201600080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 05/09/2017] [Accepted: 05/11/2017] [Indexed: 11/27/2022]
Affiliation(s)
- Ngoc-Minh Nguyen
- Inserm; U955; Equipe 13; Biomécanique & Appareil Respiratoire; Créteil Cedex F-94010 France
- Université Paris Est; UMR S955, UPEC Créteil Cedex F-94010 France
- CNRS; ERL 7240 Créteil Cedex F-94010 France
| | - Christelle Angely
- Inserm; U955; Equipe 13; Biomécanique & Appareil Respiratoire; Créteil Cedex F-94010 France
- Université Paris Est; UMR S955, UPEC Créteil Cedex F-94010 France
- CNRS; ERL 7240 Créteil Cedex F-94010 France
| | - Sofia Andre Dias
- Inserm; U955; Equipe 13; Biomécanique & Appareil Respiratoire; Créteil Cedex F-94010 France
- Université Paris Est; UMR S955, UPEC Créteil Cedex F-94010 France
- CNRS; ERL 7240 Créteil Cedex F-94010 France
| | - Emmanuelle Planus
- Institute for Advanced Biosciences (IAB); Centre de Recherche UGA/Inserm U1209/CNRS UMR 5309; La Tronche 38700 France
| | - Marcel Filoche
- Inserm; U955; Equipe 13; Biomécanique & Appareil Respiratoire; Créteil Cedex F-94010 France
- Université Paris Est; UMR S955, UPEC Créteil Cedex F-94010 France
- CNRS; ERL 7240 Créteil Cedex F-94010 France
- Laboratoire de Physique de la Matière Condensée; Ecole Polytechnique; CNRS; Université Paris Saclay; Palaiseau 91128 France
| | - Gabriel Pelle
- Inserm; U955; Equipe 13; Biomécanique & Appareil Respiratoire; Créteil Cedex F-94010 France
- Université Paris Est; UMR S955, UPEC Créteil Cedex F-94010 France
- CNRS; ERL 7240 Créteil Cedex F-94010 France
- AP-HP; Groupe Hospitalier H. Mondor - A. Chenevier; Service des Explorations Fonctionnelles; Créteil Cedex F-94010 France
| | - Bruno Louis
- Inserm; U955; Equipe 13; Biomécanique & Appareil Respiratoire; Créteil Cedex F-94010 France
- Université Paris Est; UMR S955, UPEC Créteil Cedex F-94010 France
- CNRS; ERL 7240 Créteil Cedex F-94010 France
| | - Daniel Isabey
- Inserm; U955; Equipe 13; Biomécanique & Appareil Respiratoire; Créteil Cedex F-94010 France
- Université Paris Est; UMR S955, UPEC Créteil Cedex F-94010 France
- CNRS; ERL 7240 Créteil Cedex F-94010 France
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117
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Dufrêne YF, Ando T, Garcia R, Alsteens D, Martinez-Martin D, Engel A, Gerber C, Müller DJ. Imaging modes of atomic force microscopy for application in molecular and cell biology. NATURE NANOTECHNOLOGY 2017; 12:295-307. [PMID: 28383040 DOI: 10.1038/nnano.2017.45] [Citation(s) in RCA: 532] [Impact Index Per Article: 66.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 02/23/2017] [Indexed: 05/22/2023]
Abstract
Atomic force microscopy (AFM) is a powerful, multifunctional imaging platform that allows biological samples, from single molecules to living cells, to be visualized and manipulated. Soon after the instrument was invented, it was recognized that in order to maximize the opportunities of AFM imaging in biology, various technological developments would be required to address certain limitations of the method. This has led to the creation of a range of new imaging modes, which continue to push the capabilities of the technique today. Here, we review the basic principles, advantages and limitations of the most common AFM bioimaging modes, including the popular contact and dynamic modes, as well as recently developed modes such as multiparametric, molecular recognition, multifrequency and high-speed imaging. For each of these modes, we discuss recent experiments that highlight their unique capabilities.
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Affiliation(s)
- Yves F Dufrêne
- Institute of Life Sciences and Walloon Excellence in Life Sciences and Biotechnology (WELBIO), Université catholique de Louvain, Croix du Sud 4-5, bte L7.07.06., B-1348 Louvain-la-Neuve, Belgium
| | - Toshio Ando
- Department of Physics, Kanazawa University, Kanazawa 920-1192, Japan
| | - Ricardo Garcia
- Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
| | - David Alsteens
- Institute of Life Sciences and Walloon Excellence in Life Sciences and Biotechnology (WELBIO), Université catholique de Louvain, Croix du Sud 4-5, bte L7.07.06., B-1348 Louvain-la-Neuve, Belgium
| | - David Martinez-Martin
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Mattenstrasse 28, 4056 Basel, Switzerland
| | - Andreas Engel
- Department of BioNanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Christoph Gerber
- Swiss Nanoscience Institute, University of Basel, Klingelbergstrasse 80, 4057 Basel, Switzerland
| | - Daniel J Müller
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Mattenstrasse 28, 4056 Basel, Switzerland
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118
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Giusto E, Donegà M, Dumitru AC, Foschi G, Casalini S, Bianchi M, Leonardi T, Russo A, Occhipinti LG, Biscarini F, Garcia R, Pluchino S. Interfacing Polymers and Tissues: Quantitative Local Assessment of the Foreign Body Reaction of Mononuclear Phagocytes to Polymeric Materials. ACTA ACUST UNITED AC 2017; 1:e1700021. [DOI: 10.1002/adbi.201700021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Indexed: 01/08/2023]
Affiliation(s)
- Elena Giusto
- Department of Clinical Neurosciences; Wellcome Trust-Medical Research Council Stem Cell Institute and National Institute for Health Research Biomedical Research Centre; University of Cambridge; Hills Road Cambridge CB2 0HA UK
| | - Matteo Donegà
- Department of Clinical Neurosciences; Wellcome Trust-Medical Research Council Stem Cell Institute and National Institute for Health Research Biomedical Research Centre; University of Cambridge; Hills Road Cambridge CB2 0HA UK
| | - Andra C. Dumitru
- Instituto de Ciencia de Materiales de Madrid; CSIC; Sor Juana Inés de la Cruz 3 28049 Madrid Spain
| | - Giulia Foschi
- Dipartimento di Scienze della Vita; Università di Modena and Reggio Emilia; Via Campi 103 41125 Modena Italy
| | - Stefano Casalini
- Dipartimento di Scienze della Vita; Università di Modena and Reggio Emilia; Via Campi 103 41125 Modena Italy
| | - Michele Bianchi
- Laboratorio di NanoBiotecnologie-Istituto Ortopedico Rizzoli; Via di Barbiano 1/10 40136 Bologna Italy
| | - Tommaso Leonardi
- Department of Clinical Neurosciences; Wellcome Trust-Medical Research Council Stem Cell Institute and National Institute for Health Research Biomedical Research Centre; University of Cambridge; Hills Road Cambridge CB2 0HA UK
- The EMBL-European Bioinformatics Institute; Wellcome Trust Genome Campus Hinxton Cambridge CB10 1SD UK
| | - Alessandro Russo
- Laboratorio di NanoBiotecnologie-Istituto Ortopedico Rizzoli; Via di Barbiano 1/10 40136 Bologna Italy
| | | | - Fabio Biscarini
- Dipartimento di Scienze della Vita; Università di Modena and Reggio Emilia; Via Campi 103 41125 Modena Italy
| | - Ricardo Garcia
- Instituto de Ciencia de Materiales de Madrid; CSIC; Sor Juana Inés de la Cruz 3 28049 Madrid Spain
| | - Stefano Pluchino
- Department of Clinical Neurosciences; Wellcome Trust-Medical Research Council Stem Cell Institute and National Institute for Health Research Biomedical Research Centre; University of Cambridge; Hills Road Cambridge CB2 0HA UK
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119
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Lipid-dependent conformational dynamics underlie the functional versatility of T-cell receptor. Cell Res 2017; 27:505-525. [PMID: 28337984 DOI: 10.1038/cr.2017.42] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 01/19/2017] [Accepted: 02/09/2017] [Indexed: 01/11/2023] Open
Abstract
T-cell receptor-CD3 complex (TCR) is a versatile signaling machine that can initiate antigen-specific immune responses based on various biochemical changes of CD3 cytoplasmic domains, but the underlying structural basis remains elusive. Here we developed biophysical approaches to study the conformational dynamics of CD3ε cytoplasmic domain (CD3εCD). At the single-molecule level, we found that CD3εCD could have multiple conformational states with different openness of three functional motifs, i.e., ITAM, BRS and PRS. These conformations were generated because different regions of CD3εCD had heterogeneous lipid-binding properties and therefore had heterogeneous dynamics. Live-cell imaging experiments demonstrated that different antigen stimulations could stabilize CD3εCD at different conformations. Lipid-dependent conformational dynamics thus provide structural basis for the versatile signaling property of TCR.
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120
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Suki B, Parameswaran H, Imsirovic J, Bartolák-Suki E. Regulatory Roles of Fluctuation-Driven Mechanotransduction in Cell Function. Physiology (Bethesda) 2017; 31:346-58. [PMID: 27511461 DOI: 10.1152/physiol.00051.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cells in the body are exposed to irregular mechanical stimuli. Here, we review the so-called fluctuation-driven mechanotransduction in which stresses stretching cells vary on a cycle-by-cycle basis. We argue that such mechanotransduction is an emergent network phenomenon and offer several potential mechanisms of how it regulates cell function. Several examples from the vasculature, the lung, and tissue engineering are discussed. We conclude with a list of important open questions.
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Affiliation(s)
- Béla Suki
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
| | | | - Jasmin Imsirovic
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
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121
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Gaub BM, Müller DJ. Mechanical Stimulation of Piezo1 Receptors Depends on Extracellular Matrix Proteins and Directionality of Force. NANO LETTERS 2017; 17:2064-2072. [PMID: 28164706 DOI: 10.1021/acs.nanolett.7b00177] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Piezo receptors convert mechanical forces into electrical signals. In mammals, they play important roles in basic physiological functions including proprioception, sensation of touch, and vascular development. However, basic receptor properties like the gating mechanism, the interaction with extracellular matrix (ECM) proteins, and the response to mechanical stimulation, remain poorly understood. Here, we establish an atomic force microscopy (AFM)-based assay to mechanically stimulate Piezo1 receptors in living animal cells, while monitoring receptor activation in real-time using functional calcium imaging. Our experiments show that in the absence of ECM proteins Piezo1 receptors are relatively insensitive to mechanical forces pushing the cellular membrane, whereas they can hardly be activated by mechanically pulling the membrane. Yet, if conjugated with Matrigel, a mix of ECM proteins, the receptors become sensitized. Thereby, forces pulling the cellular membrane activate the receptor much more efficiently compared to pushing forces. Finally, we found that collagen IV, a component of the basal lamina, which forms a cohesive network and mechanical connection between cells, sensitizes Piezo1 receptors to mechanical pulling.
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Affiliation(s)
- Benjamin M Gaub
- Department of Biosystems Science and Engineering, ETH Zurich , 4058 Basel, Switzerland
| | - Daniel J Müller
- Department of Biosystems Science and Engineering, ETH Zurich , 4058 Basel, Switzerland
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122
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Oriola D, Alert R, Casademunt J. Fluidization and Active Thinning by Molecular Kinetics in Active Gels. PHYSICAL REVIEW LETTERS 2017; 118:088002. [PMID: 28282157 DOI: 10.1103/physrevlett.118.088002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Indexed: 05/13/2023]
Abstract
We derive the constitutive equations of an active polar gel from a model for the dynamics of elastic molecules that link polar elements. Molecular binding kinetics induces the fluidization of the material, giving rise to Maxwell viscoelasticity and, provided that detailed balance is broken, to the generation of active stresses. We give explicit expressions for the transport coefficients of active gels in terms of molecular properties, including nonlinear contributions on the departure from equilibrium. In particular, when activity favors linker unbinding, we predict a decrease of viscosity with activity-active thinning-of kinetic origin, which could explain some experimental results on the cell cortex. By bridging the molecular and hydrodynamic scales, our results could help understand the interplay between molecular perturbations and the mechanics of cells and tissues.
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Affiliation(s)
- David Oriola
- Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Avinguda Diagonal 647 and Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain
| | - Ricard Alert
- Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Avinguda Diagonal 647 and Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain
| | - Jaume Casademunt
- Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Avinguda Diagonal 647 and Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain
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123
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Cóndor M, García-Aznar JM. A phenomenological cohesive model for the macroscopic simulation of cell-matrix adhesions. Biomech Model Mechanobiol 2017; 16:1207-1224. [PMID: 28213831 DOI: 10.1007/s10237-017-0883-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 01/31/2017] [Indexed: 01/05/2023]
Abstract
Cell adhesion is crucial for cells to not only physically interact with each other but also sense their microenvironment and respond accordingly. In fact, adherent cells can generate physical forces that are transmitted to the surrounding matrix, regulating the formation of cell-matrix adhesions. The main purpose of this work is to develop a computational model to simulate the dynamics of cell-matrix adhesions through a cohesive formulation within the framework of the finite element method and based on the principles of continuum damage mechanics. This model enables the simulation of the mechanical adhesion between cell and extracellular matrix (ECM) as regulated by local multidirectional forces and thus predicts the onset and growth of the adhesion. In addition, this numerical approach allows the simulation of the cell as a whole, as it models the complete mechanical interaction between cell and ECM. As a result, we can investigate and quantify how different mechanical conditions in the cell (e.g., contractile forces, actin cytoskeletal properties) or in the ECM (e.g., stiffness, external forces) can regulate the dynamics of cell-matrix adhesions.
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Affiliation(s)
- M Cóndor
- Department of Mechanical Engineering, Aragón Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain
| | - J M García-Aznar
- Department of Mechanical Engineering, Aragón Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain.
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124
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Alsteens D, Newton R, Schubert R, Martinez-Martin D, Delguste M, Roska B, Müller DJ. Nanomechanical mapping of first binding steps of a virus to animal cells. NATURE NANOTECHNOLOGY 2017; 12:177-183. [PMID: 27798607 DOI: 10.1038/nnano.2016.228] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 09/18/2016] [Indexed: 05/23/2023]
Abstract
Viral infection is initiated when a virus binds to cell surface receptors. Because the cell membrane is dynamic and heterogeneous, imaging living cells and simultaneously quantifying the first viral binding events is difficult. Here, we show an atomic force and confocal microscopy set-up that allows the surface receptor landscape of cells to be imaged and the virus binding events within the first millisecond of contact with the cell to be mapped at high resolution (<50 nm). We present theoretical approaches to contour the free-energy landscape of early binding events between an engineered virus and cell surface receptors. We find that the first bond formed between the viral glycoprotein and its cognate cell surface receptor has relatively low lifetime and free energy, but this increases as additional bonds form rapidly (≤1 ms). The formation of additional bonds occurs with positive allosteric modulation and the three binding sites of the viral glycoprotein are quickly occupied. Our quantitative approach can be readily applied to study the binding of other viruses to animal cells.
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Affiliation(s)
- David Alsteens
- ETH Zürich, Department of Biosystems Science and Engineering, 4058 Basel, Switzerland
- Université Catholique de Louvain, Institute of Life Sciences, 1348 Louvain-La-Neuve, Belgium
| | - Richard Newton
- ETH Zürich, Department of Biosystems Science and Engineering, 4058 Basel, Switzerland
| | - Rajib Schubert
- ETH Zürich, Department of Biosystems Science and Engineering, 4058 Basel, Switzerland
| | - David Martinez-Martin
- ETH Zürich, Department of Biosystems Science and Engineering, 4058 Basel, Switzerland
| | - Martin Delguste
- Université Catholique de Louvain, Institute of Life Sciences, 1348 Louvain-La-Neuve, Belgium
| | - Botond Roska
- Friedrich Miescher Institute (FMI), 4058 Basel, Switzerland
- Department of Ophthalmology, University of Basel, 4056 Basel, Switzerland
| | - Daniel J Müller
- ETH Zürich, Department of Biosystems Science and Engineering, 4058 Basel, Switzerland
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125
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Cellular Shear Adhesion Force Measurement and Simultaneous Imaging by Atomic Force Microscope. J Med Biol Eng 2017. [DOI: 10.1007/s40846-016-0206-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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126
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Spillane KM, Tolar P. B cell antigen extraction is regulated by physical properties of antigen-presenting cells. J Cell Biol 2017; 216:217-230. [PMID: 27923880 PMCID: PMC5223605 DOI: 10.1083/jcb.201607064] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 10/14/2016] [Accepted: 11/17/2016] [Indexed: 01/25/2023] Open
Abstract
Antibody production and affinity maturation are driven by B cell extraction and internalization of antigen from immune synapses. However, the extraction mechanism remains poorly understood. Here we develop DNA-based nanosensors to interrogate two previously proposed mechanisms, enzymatic liberation and mechanical force. Using antigens presented by either artificial substrates or live cells, we show that B cells primarily use force-dependent extraction and resort to enzymatic liberation only if mechanical forces fail to retrieve antigen. The use of mechanical forces renders antigen extraction sensitive to the physical properties of the presenting cells. We show that follicular dendritic cells are stiff cells that promote strong B cell pulling forces and stringent affinity discrimination. In contrast, dendritic cells are soft and promote acquisition of low-affinity antigens through low forces. Thus, the mechanical properties of B cell synapses regulate antigen extraction, suggesting that distinct properties of presenting cells support different stages of B cell responses.
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MESH Headings
- Animals
- Antibody Affinity
- Antigen Presentation
- Antigens/immunology
- Antigens/metabolism
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- Biosensing Techniques
- Cells, Cultured
- Dendritic Cells/immunology
- Dendritic Cells/metabolism
- Dendritic Cells, Follicular/immunology
- Dendritic Cells, Follicular/metabolism
- Elasticity
- Female
- Genotype
- Immunoglobulin kappa-Chains/genetics
- Immunoglobulin kappa-Chains/immunology
- Immunoglobulin kappa-Chains/metabolism
- Immunological Synapses/immunology
- Immunological Synapses/metabolism
- Male
- Mice, Inbred C57BL
- Mice, Knockout
- Nanotechnology/methods
- Phenotype
- Receptors, Antigen, B-Cell/immunology
- Receptors, Antigen, B-Cell/metabolism
- Stress, Mechanical
- Time Factors
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Affiliation(s)
- Katelyn M Spillane
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London NW1 1AT, England, UK
- Division of Immunology and Inflammation, Imperial College London, London SW7 2AZ, England, UK
| | - Pavel Tolar
- Immune Receptor Activation Laboratory, The Francis Crick Institute, London NW1 1AT, England, UK
- Division of Immunology and Inflammation, Imperial College London, London SW7 2AZ, England, UK
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127
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Hodges E, Cooke BM, Sevick EM, Searles DJ, Dünweg B, Prakash JR. Equilibrium binding energies from fluctuation theorems and force spectroscopy simulations. SOFT MATTER 2016; 12:9803-9820. [PMID: 27858055 DOI: 10.1039/c6sm02549h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Brownian dynamics simulations are used to study the detachment of a particle from a substrate. Although the model is simple and generic, we attempt to map its energy, length and time scales onto a specific experimental system, namely a bead that is weakly bound to a cell and then removed by an optical tweezer. The external driving force arises from the combined optical tweezer and substrate potentials, and thermal fluctuations are taken into account by a Brownian force. The Jarzynski equality and Crooks fluctuation theorem are applied to obtain the equilibrium free energy difference between the final and initial states. To this end, we sample non-equilibrium work trajectories for various tweezer pulling rates. We argue that this methodology should also be feasible experimentally for the envisioned system. Furthermore, we outline how the measurement of a whole free energy profile would allow the experimentalist to retrieve the unknown substrate potential by means of a suitable deconvolution. The influence of the pulling rate on the accuracy of the results is investigated, and umbrella sampling is used to obtain the equilibrium probability of particle escape for a variety of trap potentials.
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Affiliation(s)
- Emma Hodges
- Department of Chemical Engineering, Monash University, Melbourne, VIC 3800, Australia. and Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, VIC 3800, Australia
| | - B M Cooke
- Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, VIC 3800, Australia
| | - E M Sevick
- Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Debra J Searles
- AIBN Centre for Theoretical and Computational Molecular Science, University of Queensland, Brisbane, QLD 4072, Australia and School of Chemical and Molecular Biosciences, University of Queensland, Brisbane, QLD 4072, Australia
| | - B Dünweg
- Department of Chemical Engineering, Monash University, Melbourne, VIC 3800, Australia. and Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany and Condensed Matter Physics, TU Darmstadt, Hochschulstraße 12, 64289 Darmstadt, Germany
| | - J Ravi Prakash
- Department of Chemical Engineering, Monash University, Melbourne, VIC 3800, Australia.
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128
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Manibog K, Yen CF, Sivasankar S. Measuring Force-Induced Dissociation Kinetics of Protein Complexes Using Single-Molecule Atomic Force Microscopy. Methods Enzymol 2016; 582:297-320. [PMID: 28062039 DOI: 10.1016/bs.mie.2016.08.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Proteins respond to mechanical force by undergoing conformational changes and altering the kinetics of their interactions. However, the biophysical relationship between mechanical force and the lifetime of protein complexes is not completely understood. In this chapter, we provide a step-by-step tutorial on characterizing the force-dependent regulation of protein interactions using in vitro and in vivo single-molecule force clamp measurements with an atomic force microscope (AFM). While we focus on the force-induced dissociation of E-cadherins, a critical cell-cell adhesion protein, the approaches described here can be readily adapted to study other protein complexes. We begin this chapter by providing a brief overview of theoretical models that describe force-dependent kinetics of biomolecular interactions. Next, we present step-by-step methods for measuring the response of single receptor-ligand bonds to tensile force in vitro. Finally, we describe methods for quantifying the mechanical response of single protein complexes on the surface of living cells. We describe general protocols for conducting such measurements, including sample preparation, AFM force clamp measurements, and data analysis. We also highlight critical limitations in current technologies and discuss solutions to these challenges.
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Affiliation(s)
- K Manibog
- Iowa State University, Ames, IA, United States; Ames Laboratory, U.S. Department of Energy, Ames, IA, United States
| | - C F Yen
- Iowa State University, Ames, IA, United States; Ames Laboratory, U.S. Department of Energy, Ames, IA, United States
| | - S Sivasankar
- Iowa State University, Ames, IA, United States; Ames Laboratory, U.S. Department of Energy, Ames, IA, United States.
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129
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Bui VC, Nguyen TH. Insights into the interaction of CD4 with anti-CD4 antibodies. Immunobiology 2016; 222:148-154. [PMID: 27773661 DOI: 10.1016/j.imbio.2016.10.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 10/15/2016] [Indexed: 01/13/2023]
Abstract
Knowledge about the mechanism by which some antibodies can block HIV-1 entry is critical to our understanding of their function and may offer new avenues for controlling the adhesion of HIV-1 to the host cells. While much progress has been made, this mechanism remains unclear. Here, atomic force microscopy, isothermal titration calorimetry (ITC), and circular dichroism spectroscopy were used to measure some biophysical characteristics of the interaction of four-domains (D1-D4) membrane protein CD4 with anti-D3 antibody OKT4 and with HIV-1 entry blocking anti-D1 antibody Leu3a. The results showed that at 37°C they bind with similar binding strength, thermodynamics, and kinetics but with different assembly states. Further analyzing the interactions at different temperatures by ITC showed that binding of CD4 with Leu3a is characteristic for specific hydrophobic binding as well as for protein folding while with OKT4 comes from an extensive additional hydration upon binding and charge-related interactions within the binding site. Comparing these characteristics with those of HIV-1 gp120-CD4 interaction revealed that Leu3a binds to CD4 faster than HIV-1 followed by changing local structure of D1 to which HIV-1 binds leading to a prevention of viral entry.
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Affiliation(s)
- Van-Chien Bui
- Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular Diseases, University Medicine Greifswald, 17489 Greifswald, Germany; Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Thi-Huong Nguyen
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, 17475 Greifswald, Germany.
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130
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Li L, Zhang W, Wang J. A viscoelastic-stochastic model of the effects of cytoskeleton remodelling on cell adhesion. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160539. [PMID: 27853571 PMCID: PMC5098996 DOI: 10.1098/rsos.160539] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 09/21/2016] [Indexed: 05/07/2023]
Abstract
Cells can adapt their mechanical properties through cytoskeleton remodelling in response to external stimuli when the cells adhere to the extracellular matrix (ECM). Many studies have investigated the effects of cell and ECM elasticity on cell adhesion. However, experiments determined that cells are viscoelastic and exhibiting stress relaxation, and the mechanism behind the effect of cellular viscoelasticity on the cell adhesion behaviour remains unclear. Therefore, we propose a theoretical model of a cluster of ligand-receptor bonds between two dissimilar viscoelastic media subjected to an applied tensile load. In this model, the distribution of interfacial traction is assumed to follow classical continuum viscoelastic equations, whereas the rupture and rebinding of individual molecular bonds are governed by stochastic equations. On the basis of this model, we determined that viscosity can significantly increase the lifetime, stability and dynamic strength of the adhesion cluster of molecular bonds, because deformation relaxation attributed to the viscoelastic property can increase the rebinding probability of each open bond and reduce the stress concentration in the adhesion area.
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Affiliation(s)
| | | | - Jizeng Wang
- Key Laboratory of Mechanics on Disaster and Environment in Western China, Ministry of Education, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000, People's Republic of China
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131
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Wang X, Sun J, Xu Q, Chowdhury F, Roein-Peikar M, Wang Y, Ha T. Integrin Molecular Tension within Motile Focal Adhesions. Biophys J 2016; 109:2259-67. [PMID: 26636937 DOI: 10.1016/j.bpj.2015.10.029] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 10/19/2015] [Accepted: 10/26/2015] [Indexed: 12/12/2022] Open
Abstract
Forces transmitted by integrins regulate many important cellular functions. Previously, we developed tension gauge tether (TGT) as a molecular force sensor and determined the threshold tension across a single integrin-ligand bond, termed integrin tension, required for initial cell adhesion. Here, we used fluorescently labeled TGTs to study the magnitude and spatial distribution of integrin tension on the cell-substratum interface. We observed two distinct levels of integrin tension. A >54 pN molecular tension is transmitted by clustered integrins in motile focal adhesions (FAs) and such force is generated by actomyosin, whereas the previously reported ∼40 pN integrin tension is transmitted by integrins before FA formation and is independent of actomyosin. We then studied FA motility using a TGT-coated surface as a fluorescent canvas, which records the history of integrin force activity. Our data suggest that the region of the strongest integrin force overlaps with the center of a motile FA within 0.2 μm resolution. We also found that FAs move in pairs and that the asymmetry in the motility of an FA pair is dependent on the initial FA locations on the cell-substratum interface.
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Affiliation(s)
- Xuefeng Wang
- Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois; Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Department of Physics and Astronomy, Iowa State University, Ames, Iowa.
| | - Jie Sun
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Qian Xu
- Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Farhan Chowdhury
- Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Mehdi Roein-Peikar
- Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Yingxiao Wang
- Bioengineering Department, University of California San Diego, La Jolla, California
| | - Taekjip Ha
- Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois; Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Howard Hughes Medical Institute, Johns Hopkins University, Baltimore, Maryland; Department of Biophysics & Biophysical Chemistry, Department of Biophysics, and Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
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132
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Sessions JW, Lewis TE, Skousen CS, Hope S, Jensen BD. The effect of injection speed and serial injection on propidium iodide entry into cultured HeLa and primary neonatal fibroblast cells using lance array nanoinjection. SPRINGERPLUS 2016; 5:1093. [PMID: 27468394 PMCID: PMC4947087 DOI: 10.1186/s40064-016-2757-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 07/05/2016] [Indexed: 01/01/2023]
Abstract
Background Although site-directed genetic engineering has greatly improved in recent years, particularly with the implementation of CRISPR-Cas9, the ability to deliver these molecular constructs to a wide variety of cell types without adverse reaction is still a challenge. One non-viral transfection method designed to address this challenge is a MEMS based biotechnology described previously as lance array nanoinjection (LAN). LAN delivery of molecular loads is based upon the combinational use of electrical manipulation of loads of interest and physical penetration of target cell membranes. This work explores an original procedural element to nanoinjection by investigating the effects of the speed of injection and also the ability to serially inject the same sample. Results Initial LAN experimentation demonstrated that injecting at speeds of 0.08 mm/s resulted in 99.3 % of cultured HeLa 229 cells remaining adherent to the glass slide substrate used to stage the injection process. These results were then utilized to examine whether or not target cells could be injected multiple times (1, 2, and 3 times) since the injection process was not pulling the cells off of the glass slide. Using two different current control settings (1.5 and 3.0 mA) and two different cell types (HeLa 229 cells and primary neonatal fibroblasts [BJ(ATCC® CRL-2522™)], treatment samples were injected with propidium iodide (PI), a cell membrane impermeable nucleic acid dye, to assess the degree of molecular load delivery. Results from the serial injection work indicate that HeLa cells treated with 3.0 mA and injected twice (×2) had the greatest mean PI uptake of 60.47 % and that neonatal fibroblasts treated with the same protocol reached mean PI uptake rates of 20.97 %. Conclusions Both experimental findings are particularly useful because it shows that greater molecular modification rates can be achieved by multiple, serial injections via a slower injection process.
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Affiliation(s)
- John W Sessions
- Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602 USA
| | - Tyler E Lewis
- Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602 USA
| | - Craig S Skousen
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT 84602 USA
| | - Sandra Hope
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT 84602 USA
| | - Brian D Jensen
- Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602 USA
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133
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Yi E, Sato S, Takahashi A, Parameswaran H, Blute TA, Bartolák-Suki E, Suki B. Mechanical Forces Accelerate Collagen Digestion by Bacterial Collagenase in Lung Tissue Strips. Front Physiol 2016; 7:287. [PMID: 27462275 PMCID: PMC4940411 DOI: 10.3389/fphys.2016.00287] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 06/24/2016] [Indexed: 11/13/2022] Open
Abstract
Most tissues in the body are under mechanical tension, and while enzymes mediate many cellular and extracellular processes, the effects of mechanical forces on enzyme reactions in the native extracellular matrix (ECM) are not fully understood. We hypothesized that physiological levels of mechanical forces are capable of modifying the activity of collagenase, a key remodeling enzyme of the ECM. To test this, lung tissue Young's modulus and a nonlinearity index characterizing the shape of the stress-strain curve were measured in the presence of bacterial collagenase under static uniaxial strain of 0, 20, 40, and 80%, as well as during cyclic mechanical loading with strain amplitudes of ±10 or ±20% superimposed on 40% static strain, and frequencies of 0.1 or 1 Hz. Confocal and electron microscopy was used to determine and quantify changes in ECM structure. Generally, mechanical loading increased the effects of enzyme activity characterized by an irreversible decline in stiffness and tissue deterioration seen on both confocal and electron microscopic images. However, a static strain of 20% provided protection against digestion compared to both higher and lower strains. The decline in stiffness during digestion positively correlated with the increase in equivalent alveolar diameters and negatively correlated with the nonlinearity index. These results suggest that the decline in stiffness results from rupture of collagen followed by load transfer and subsequent rupture of alveolar walls. This study may provide new understanding of the role of collagen degradation in general tissue remodeling and disease progression.
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Affiliation(s)
- Eunice Yi
- Cell and Tissue Mechanics, Department of Biomedical Engineering, Boston University Boston, MA, USA
| | - Susumu Sato
- Cell and Tissue Mechanics, Department of Biomedical Engineering, Boston University Boston, MA, USA
| | - Ayuko Takahashi
- Cell and Tissue Mechanics, Department of Biomedical Engineering, Boston University Boston, MA, USA
| | | | - Todd A Blute
- Cell and Tissue Mechanics, Department of Biomedical Engineering, Boston University Boston, MA, USA
| | - Erzsébet Bartolák-Suki
- Cell and Tissue Mechanics, Department of Biomedical Engineering, Boston University Boston, MA, USA
| | - Béla Suki
- Cell and Tissue Mechanics, Department of Biomedical Engineering, Boston University Boston, MA, USA
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134
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Vargas DA, Sun M, Sadykov K, Kukuruzinska MA, Zaman MH. The Integrated Role of Wnt/β-Catenin, N-Glycosylation, and E-Cadherin-Mediated Adhesion in Network Dynamics. PLoS Comput Biol 2016; 12:e1005007. [PMID: 27427963 PMCID: PMC4948889 DOI: 10.1371/journal.pcbi.1005007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 05/30/2016] [Indexed: 11/24/2022] Open
Abstract
The cellular network composed of the evolutionarily conserved metabolic pathways of protein N-glycosylation, Wnt/β-catenin signaling pathway, and E-cadherin-mediated cell-cell adhesion plays pivotal roles in determining the balance between cell proliferation and intercellular adhesion during development and in maintaining homeostasis in differentiated tissues. These pathways share a highly conserved regulatory molecule, β-catenin, which functions as both a structural component of E-cadherin junctions and as a co-transcriptional activator of the Wnt/β-catenin signaling pathway, whose target is the N-glycosylation-regulating gene, DPAGT1. Whereas these pathways have been studied independently, little is known about the dynamics of their interaction. Here we present the first numerical model of this network in MDCK cells. Since the network comprises a large number of molecules with varying cell context and time-dependent levels of expression, it can give rise to a wide range of plausible cellular states that are difficult to track. Using known kinetic parameters for individual reactions in the component pathways, we have developed a theoretical framework and gained new insights into cellular regulation of the network. Specifically, we developed a mathematical model to quantify the fold-change in concentration of any molecule included in the mathematical representation of the network in response to a simulated activation of the Wnt/ β-catenin pathway with Wnt3a under different conditions. We quantified the importance of protein N-glycosylation and synthesis of the DPAGT1 encoded enzyme, GPT, in determining the abundance of cytoplasmic β-catenin. We confirmed the role of axin in β-catenin degradation. Finally, our data suggest that cell-cell adhesion is insensitive to E-cadherin recycling in the cell. We validate the model by inhibiting β-catenin-mediated activation of DPAGT1 expression and predicting changes in cytoplasmic β-catenin concentration and stability of E-cadherin junctions in response to DPAGT1 inhibition. We show the impact of pathway dysregulation through measurements of cell migration in scratch-wound assays. Collectively, our results highlight the importance of numerical analyses of cellular networks dynamics to gain insights into physiological processes and potential design of therapeutic strategies to prevent epithelial cell invasion in cancer.
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Affiliation(s)
- Diego A Vargas
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Meng Sun
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Khikmet Sadykov
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Maria A Kukuruzinska
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Muhammad H Zaman
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
- Howard Hughes Medical Institute, Boston University, Boston, Massachusetts, United States of America
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135
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Chang JC, Fok PW, Chou T. Bayesian Uncertainty Quantification for Bond Energies and Mobilities Using Path Integral Analysis. Biophys J 2016; 109:966-74. [PMID: 26331254 DOI: 10.1016/j.bpj.2015.07.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 06/04/2015] [Accepted: 07/14/2015] [Indexed: 12/24/2022] Open
Abstract
Dynamic single-molecule force spectroscopy is often used to distort bonds. The resulting responses, in the form of rupture forces, work applied, and trajectories of displacements, are used to reconstruct bond potentials. Such approaches often rely on simple parameterizations of one-dimensional bond potentials, assumptions on equilibrium starting states, and/or large amounts of trajectory data. Parametric approaches typically fail at inferring complicated bond potentials with multiple minima, while piecewise estimation may not guarantee smooth results with the appropriate behavior at large distances. Existing techniques, particularly those based on work theorems, also do not address spatial variations in the diffusivity that may arise from spatially inhomogeneous coupling to other degrees of freedom in the macromolecule. To address these challenges, we develop a comprehensive empirical Bayesian approach that incorporates data and regularization terms directly into a path integral. All experimental and statistical parameters in our method are estimated directly from the data. Upon testing our method on simulated data, our regularized approach requires less data and allows simultaneous inference of both complex bond potentials and diffusivity profiles. Crucially, we show that the accuracy of the reconstructed bond potential is sensitive to the spatially varying diffusivity and accurate reconstruction can be expected only when both are simultaneously inferred. Moreover, after providing a means for self-consistently choosing regularization parameters from data, we derive posterior probability distributions, allowing for uncertainty quantification.
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Affiliation(s)
- Joshua C Chang
- Mathematical Biosciences Institute, The Ohio State University, Columbus, Ohio.
| | - Pak-Wing Fok
- Department of Mathematical Sciences, University of Delaware, Newark, Delaware.
| | - Tom Chou
- Departments of Biomathematics and Mathematics, University of California Los Angeles, Los Angeles, California.
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136
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Yehoshua S, Pollari R, Milstein JN. Axial Optical Traps: A New Direction for Optical Tweezers. Biophys J 2016; 108:2759-66. [PMID: 26083913 DOI: 10.1016/j.bpj.2015.05.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 03/24/2015] [Accepted: 05/13/2015] [Indexed: 10/23/2022] Open
Abstract
Optical tweezers have revolutionized our understanding of the microscopic world. Axial optical tweezers, which apply force to a surface-tethered molecule by directly moving either the trap or the stage along the laser beam axis, offer several potential benefits when studying a range of novel biophysical phenomena. This geometry, although it is conceptually straightforward, suffers from aberrations that result in variation of the trap stiffness when the distance between the microscope coverslip and the trap focus is being changed. Many standard techniques, such as back-focal-plane interferometry, are difficult to employ in this geometry due to back-scattered light between the bead and the coverslip, whereas the noise inherent in a surface-tethered assay can severely limit the resolution of an experiment. Because of these complications, precision force spectroscopy measurements have adapted alternative geometries such as the highly successful dumbbell traps. In recent years, however, most of the difficulties inherent in constructing a precision axial optical tweezers have been solved. This review article aims to inform the reader about recent progress in axial optical trapping, as well as the potential for these devices to perform innovative biophysical measurements.
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Affiliation(s)
- Samuel Yehoshua
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Russell Pollari
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Joshua N Milstein
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.
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137
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Prakash SS. Cavitation of tumoral basement membrane as onset of cancer invasion and metastasis: physics of oncogenic homeorhesis via nonlinear mechano-metabolomics. CONVERGENT SCIENCE PHYSICAL ONCOLOGY 2016. [DOI: 10.1088/2057-1739/2/1/015001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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138
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Partola KR, Lykotrafitis G. FRAME (Force Review Automation Environment): MATLAB-based AFM data processor. J Biomech 2016; 49:1221-1224. [PMID: 26972765 DOI: 10.1016/j.jbiomech.2016.02.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/16/2016] [Accepted: 02/16/2016] [Indexed: 10/22/2022]
Abstract
Data processing of force-displacement curves generated by atomic force microscopes (AFMs) for elastic moduli and unbinding event measurements is very time consuming and susceptible to user error or bias. There is an evident need for consistent, dependable, and easy-to-use AFM data processing software. We have developed an open-source software application, the force review automation environment (or FRAME), that provides users with an intuitive graphical user interface, automating data processing, and tools for expediting manual processing. We did not observe a significant difference between manually processed and automatically processed results from the same data sets.
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139
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Knittel P, Zhang H, Kranz C, Wallace GG, Higgins MJ. Probing the PEDOT:PSS/cell interface with conductive colloidal probe AFM-SECM. NANOSCALE 2016; 8:4475-4481. [PMID: 26853382 DOI: 10.1039/c5nr07155k] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
UNLABELLED Conductive colloidal probe Atomic Force-Scanning Electrochemical Microscopy (AFM-SECM) is a new approach, which employs electrically insulated AFM probes except for a gold-coated colloid located at the end of the cantilever. Hence, force measurements can be performed while biasing the conductive colloid under physiological conditions. Moreover, such colloids can be modified by electrochemical polymerization resulting, e.g. in conductive polymer-coated spheres, which in addition may be loaded with specific dopants. In contrast to other AFM-based single cell force spectroscopy measurements, these probes allow adhesion measurements at the cell-biomaterial interface on multiple cells in a rapid manner while the properties of the polymer can be changed by applying a bias. In addition, spatially resolved electrochemical information e.g., oxygen reduction can be obtained simultaneously. Conductive colloid AFM-SECM probes modified with poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate ( PEDOT PSS) are used for single cell force measurements in mouse fibroblasts and single cell interactions are investigated as a function of the applied potential.
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Affiliation(s)
- P Knittel
- University of Ulm, Institute of Analytical and Bioanalytical Chemistry, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
| | - H Zhang
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, 2522, Australia.
| | - C Kranz
- University of Ulm, Institute of Analytical and Bioanalytical Chemistry, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
| | - G G Wallace
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, 2522, Australia.
| | - M J Higgins
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, 2522, Australia.
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140
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Haining AWM, Lieberthal TJ, Hernández ADR. Talin: a mechanosensitive molecule in health and disease. FASEB J 2016; 30:2073-85. [DOI: 10.1096/fj.201500080r] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/09/2016] [Indexed: 12/22/2022]
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141
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Horton ER, Humphries JD, Stutchbury B, Jacquemet G, Ballestrem C, Barry ST, Humphries MJ. Modulation of FAK and Src adhesion signaling occurs independently of adhesion complex composition. J Cell Biol 2016; 212:349-64. [PMID: 26833789 PMCID: PMC4739608 DOI: 10.1083/jcb.201508080] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 01/06/2016] [Indexed: 01/15/2023] Open
Abstract
Integrin adhesion complexes (IACs) form mechanochemical connections between the extracellular matrix and actin cytoskeleton and mediate phenotypic responses via posttranslational modifications. Here, we investigate the modularity and robustness of the IAC network to pharmacological perturbation of the key IAC signaling components focal adhesion kinase (FAK) and Src. FAK inhibition using AZ13256675 blocked FAK(Y397) phosphorylation but did not alter IAC composition, as reported by mass spectrometry. IAC composition was also insensitive to Src inhibition using AZD0530 alone or in combination with FAK inhibition. In contrast, kinase inhibition substantially reduced phosphorylation within IACs, cell migration and proliferation. Furthermore using fluorescence recovery after photobleaching, we found that FAK inhibition increased the exchange rate of a phosphotyrosine (pY) reporter (dSH2) at IACs. These data demonstrate that kinase-dependent signal propagation through IACs is independent of gross changes in IAC composition. Together, these findings demonstrate a general separation between the composition of IACs and their ability to relay pY-dependent signals.
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Affiliation(s)
- Edward R Horton
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, England, UK
| | - Jonathan D Humphries
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, England, UK
| | - Ben Stutchbury
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, England, UK
| | - Guillaume Jacquemet
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, England, UK
| | - Christoph Ballestrem
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, England, UK
| | - Simon T Barry
- Oncology iMed, AstraZeneca, Cheshire SK10 4TG, England, UK
| | - Martin J Humphries
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, England, UK
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142
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Jaklenec A, Anselmo AC, Hong J, Vegas AJ, Kozminsky M, Langer R, Hammond PT, Anderson DG. High Throughput Layer-by-Layer Films for Extracting Film Forming Parameters and Modulating Film Interactions with Cells. ACS APPLIED MATERIALS & INTERFACES 2016; 8:2255-2261. [PMID: 26713554 DOI: 10.1021/acsami.5b11081] [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] [Indexed: 06/05/2023]
Abstract
A high-throughput approach which automates the synthesis of polyelectrolyte-based layer-by-layer films (HT-LbL) to facilitate rapid film generation, systematic film characterization, and rational investigations into their interactions with cells is described. Key parameters, such as polyelectrolyte adsorption time and polyelectrolyte deposition pH, were used to modulate LbL film growth to create LbL films of distinct thicknesses using the widely utilized polyelectrolytes poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA). We highlight how HT-LbL can be used to rapidly characterize film-forming parameters and robustly create linearly growing films of various molecular architectures. Film thickness and growth rates of HT-LbL films were shown to increase as a function of adsorption time. Subsequently, we investigated the role that polyelectrolyte solution pH (ranging from 2.5 to 9) has in forming molecularly distinct films of weak polyelectrolytes and report the effect this has on modulating cell attachment and spreading. Films synthesized at PAA-pH of 5.5 and PAH-pH 2.5-5.5 exhibited the highest cellular attachment. These results indicate that HT-LbL is a robust method that can shift the paradigm regarding the use of LbL in biomedical applications as it provides a rapid method to synthesize, characterize, and screen the interactions between molecularly distinct LbL films and cells.
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Affiliation(s)
- Ana Jaklenec
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 500 Main Street, Cambridge, Massachusetts 02139, United States
| | - Aaron C Anselmo
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 500 Main Street, Cambridge, Massachusetts 02139, United States
| | - Jinkee Hong
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 500 Main Street, Cambridge, Massachusetts 02139, United States
| | - Arturo J Vegas
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 500 Main Street, Cambridge, Massachusetts 02139, United States
| | - Molly Kozminsky
- Department of Chemical Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Robert Langer
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 500 Main Street, Cambridge, Massachusetts 02139, United States
- Department of Chemical Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology , 500 Main Street, Cambridge, Massachusetts 02139, United States
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology , 500 Main Street, Cambridge, Massachusetts 02139, United States
| | - Paula T Hammond
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 500 Main Street, Cambridge, Massachusetts 02139, United States
- Department of Chemical Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Daniel G Anderson
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 500 Main Street, Cambridge, Massachusetts 02139, United States
- Department of Chemical Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology , 500 Main Street, Cambridge, Massachusetts 02139, United States
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology , 500 Main Street, Cambridge, Massachusetts 02139, United States
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143
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El-Kirat-Chatel S, Dufrêne YF. Nanoscale adhesion forces between the fungal pathogen Candida albicans and macrophages. NANOSCALE HORIZONS 2016; 1:69-74. [PMID: 32260605 DOI: 10.1039/c5nh00049a] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The development of fungal infections is tightly controlled by the interaction of fungal pathogens with host immune cells. While the recognition of specific fungal cell wall components by immune receptors has been widely investigated, the molecular forces involved are not known. In this Communication, we show the ability of single-cell force spectroscopy to quantify the specific adhesion forces between the fungal pathogen Candida albicans and macrophages. The Candida-macrophage adhesion force is strong, up to ∼3000 pN, and corresponds to multiple cumulative bonds between lectin receptors expressed on the macrophage membrane and mannan carbohydrates on the fungal cell surface. Adhesion force signatures show constant force plateaus, up to >100 μm long, reflecting the extraction of elongated tethers from the macrophage membrane, a phenomenon which may increase the duration of intercellular adhesion. Adhesion strengthens with time, suggesting that the macrophage membrane engulfs the pathogen quickly after initial contact, leading to its internalization. The force nanoscopy method developed here holds great promise for understanding and controlling the early stages of microbe-immune interactions.
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Affiliation(s)
- Sofiane El-Kirat-Chatel
- Institute of Life Sciences, Université catholique de Louvain, Croix du Sud 4-5, bte L7.07.06, 1348 Louvain-la-Neuve, Belgium.
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144
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Abstract
Cells actively sense the mechanical properties of the extracellular matrix, such as its rigidity, morphology, and deformation. The cell-matrix interaction influences a range of cellular processes, including cell adhesion, migration, and differentiation, among others. This article aims to review some of the recent progress that has been made in modeling mechanosensing in cell-matrix interactions at different length scales. The issues discussed include specific interactions between proteins, the structure and mechanosensitivity of focal adhesions, the cluster effects of the specific binding, the structure and behavior of stress fibers, cells' sensing of substrate stiffness, and cell reorientation on cyclically stretched substrates. The review concludes by looking toward future opportunities in the field and at the challenges to understanding active cell-matrix interactions.
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Affiliation(s)
- Bin Chen
- Department of Engineering Mechanics, Zhejiang University, Hangzhou 310027, China;
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145
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Mechanics of Bacterial Cells and Initial Surface Colonisation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 915:245-60. [DOI: 10.1007/978-3-319-32189-9_15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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146
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Dumitru AC, Herruzo ET, Rausell E, Ceña V, Garcia R. Unbinding forces and energies between a siRNA molecule and a dendrimer measured by force spectroscopy. NANOSCALE 2015; 7:20267-20276. [PMID: 26580848 DOI: 10.1039/c5nr04906g] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We have measured the intermolecular forces between small interference RNA (siRNA) and polyamidoamine dendrimers at the single molecular level. A single molecule force spectroscopy approach has been developed to measure the unbinding forces and energies between a siRNA molecule and polyamidoamine dendrimers deposited on a mica surface in a buffer solution. We report three types of unbinding events which are characterized by forces and free unbinding energies, respectively, of 28 pN, 0.709 eV; 38 pN, 0.722 eV; and 50 pN, 0.724 eV. These events reflect different possible electrostatic interactions between the positive charges of one or two dendrimers and the negatively charged phosphate groups of a single siRNA. We have evidence of a high binding affinity of siRNA towards polyamidoamine dendrimers that leads to a 45% probability of measuring specific unbinding events.
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Affiliation(s)
- Andra C Dumitru
- Instituto de Ciencia de Materiales de Madrid, CSIC, c/Sor Juana Ines de la Cruz 3, 28049 Madrid, Spain.
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147
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Identifying and quantifying two ligand-binding sites while imaging native human membrane receptors by AFM. Nat Commun 2015; 6:8857. [PMID: 26561004 PMCID: PMC4660198 DOI: 10.1038/ncomms9857] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 10/11/2015] [Indexed: 01/29/2023] Open
Abstract
A current challenge in life sciences is to image cell membrane receptors while characterizing their specific interactions with various ligands. Addressing this issue has been hampered by the lack of suitable nanoscopic methods. Here we address this challenge and introduce multifunctional high-resolution atomic force microscopy (AFM) to image human protease-activated receptors (PAR1) in the functionally important lipid membrane and to simultaneously localize and quantify their binding to two different ligands. Therefore, we introduce the surface chemistry to bifunctionalize AFM tips with the native receptor-activating peptide and a tris-N-nitrilotriacetic acid (tris-NTA) group binding to a His10-tag engineered to PAR1. We further introduce ways to discern between the binding of both ligands to different receptor sites while imaging native PAR1s. Surface chemistry and nanoscopic method are applicable to a range of biological systems in vitro and in vivo and to concurrently detect and localize multiple ligand-binding sites at single receptor resolution.
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148
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Burridge K, Guilluy C. Focal adhesions, stress fibers and mechanical tension. Exp Cell Res 2015; 343:14-20. [PMID: 26519907 PMCID: PMC4891215 DOI: 10.1016/j.yexcr.2015.10.029] [Citation(s) in RCA: 266] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 10/23/2015] [Indexed: 12/22/2022]
Abstract
Stress fibers and focal adhesions are complex protein arrays that produce, transmit and sense mechanical tension. Evidence accumulated over many years led to the conclusion that mechanical tension generated within stress fibers contributes to the assembly of both stress fibers themselves and their associated focal adhesions. However, several lines of evidence have recently been presented against this model. Here we discuss the evidence for and against the role of mechanical tension in driving the assembly of these structures. We also consider how their assembly is influenced by the rigidity of the substratum to which cells are adhering. Finally, we discuss the recently identified connections between stress fibers and the nucleus, and the roles that these may play, both in cell migration and regulating nuclear function.
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Affiliation(s)
- Keith Burridge
- Department of Cell Biology and Physiology, and Lineberger Comprehensive Cancer Center, 12-016 Lineberger, CB#7295, University of North Carolina, Chapel Hill, NC, USA.
| | - Christophe Guilluy
- Inserm UMR_S1087, CNRS UMR_C6291, L'institut du Thorax, and Université de Nantes, Nantes, France.
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149
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Mechanosensitivity of integrin adhesion complexes: role of the consensus adhesome. Exp Cell Res 2015; 343:7-13. [PMID: 26515553 DOI: 10.1016/j.yexcr.2015.10.025] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 10/23/2015] [Indexed: 12/17/2022]
Abstract
Cell and tissue stiffness have been known to contribute to both developmental and pathological signalling for some time, but the underlying mechanisms remain elusive. Integrins and their associated adhesion signalling complexes (IACs), which form a nexus between the cell cytoskeleton and the extracellular matrix, act as a key force sensing and transducing unit in cells. Accordingly, there has been much interest in obtaining a systems-level understanding of IAC composition. Proteomic approaches have revealed the complexity of IACs and identified a large number of components that are regulated by cytoskeletal force. Here we review the function of the consensus adhesome, an assembly of core IAC proteins that emerged from a meta-analysis of multiple proteomic datasets, in the context of mechanosensing. As IAC components have been linked to a variety of diseases involved with rigidity sensing, the field is now in a position to define the mechanosensing function of individual IAC proteins and elucidate their mechanisms of action.
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150
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Subbiah R, Jeon SB, Park K, Ahn SJ, Yun K. Investigation of cellular responses upon interaction with silver nanoparticles. Int J Nanomedicine 2015; 10 Spec Iss:191-201. [PMID: 26346562 PMCID: PMC4556294 DOI: 10.2147/ijn.s88508] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In order for nanoparticles (NPs) to be applied in the biomedical field, a thorough investigation of their interactions with biological systems is required. Although this is a growing area of research, there is a paucity of comprehensive data in cell-based studies. To address this, we analyzed the physicomechanical responses of human alveolar epithelial cells (A549), mouse fibroblasts (NIH3T3), and human bone marrow stromal cells (HS-5), following their interaction with silver nanoparticles (AgNPs). When compared with kanamycin, AgNPs exhibited moderate antibacterial activity. Cell viability ranged from ≤80% at a high AgNPs dose (40 µg/mL) to >95% at a low dose (10 µg/mL). We also used atomic force microscopy-coupled force spectroscopy to evaluate the biophysical and biomechanical properties of cells. This revealed that AgNPs treatment increased the surface roughness (P<0.001) and stiffness (P<0.001) of cells. Certain cellular changes are likely due to interaction of the AgNPs with the cell surface. The degree to which cellular morphology was altered directly proportional to the level of AgNP-induced cytotoxicity. Together, these data suggest that atomic force microscopy can be used as a potential tool to develop a biomechanics-based biomarker for the evaluation of NP-dependent cytotoxicity and cytopathology.
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Affiliation(s)
- Ramesh Subbiah
- Center for Biomaterials, Korea Institute of Science and Technology, Seoul, Republic of Korea ; Department of Biomedical Engineering, Korea University of Science and Technology, Daejon, Republic of Korea
| | - Seong Beom Jeon
- Department of Bionanotechnology, Gachon University, Gyeonggi-do, Republic of Korea ; Centre for Advanced Instrumentation, Korea Research Institute of Standard and Science, Korea University of Science and Technology, Daejeon, Republic of Korea
| | - Kwideok Park
- Center for Biomaterials, Korea Institute of Science and Technology, Seoul, Republic of Korea ; Department of Biomedical Engineering, Korea University of Science and Technology, Daejon, Republic of Korea
| | - Sang Jung Ahn
- Centre for Advanced Instrumentation, Korea Research Institute of Standard and Science, Korea University of Science and Technology, Daejeon, Republic of Korea ; Major of Nano Science, Korea University of Science and Technology, Daejeon, Republic of Korea
| | - Kyusik Yun
- Department of Bionanotechnology, Gachon University, Gyeonggi-do, Republic of Korea
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