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Atia L, Fredberg JJ. A life off the beaten track in biomechanics: Imperfect elasticity, cytoskeletal glassiness, and epithelial unjamming. BIOPHYSICS REVIEWS 2023; 4:041304. [PMID: 38156333 PMCID: PMC10751956 DOI: 10.1063/5.0179719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 11/17/2023] [Indexed: 12/30/2023]
Abstract
Textbook descriptions of elasticity, viscosity, and viscoelasticity fail to account for certain mechanical behaviors that typify soft living matter. Here, we consider three examples. First, strong empirical evidence suggests that within lung parenchymal tissues, the frictional stresses expressed at the microscale are fundamentally not of viscous origin. Second, the cytoskeleton (CSK) of the airway smooth muscle cell, as well as that of all eukaryotic cells, is more solid-like than fluid-like, yet its elastic modulus is softer than the softest of soft rubbers by a factor of 104-105. Moreover, the eukaryotic CSK expresses power law rheology, innate malleability, and fluidization when sheared. For these reasons, taken together, the CSK of the living eukaryotic cell is reminiscent of the class of materials called soft glasses, thus likening it to inert materials such as clays, pastes slurries, emulsions, and foams. Third, the cellular collective comprising a confluent epithelial layer can become solid-like and jammed, fluid-like and unjammed, or something in between. Esoteric though each may seem, these discoveries are consequential insofar as they impact our understanding of bronchospasm and wound healing as well as cancer cell invasion and embryonic development. Moreover, there are reasons to suspect that certain of these phenomena first arose in the early protist as a result of evolutionary pressures exerted by the primordial microenvironment. We have hypothesized, further, that each then became passed down virtually unchanged to the present day as a conserved core process. These topics are addressed here not only because they are interesting but also because they track the journey of one laboratory along a path less traveled by.
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Affiliation(s)
- Lior Atia
- Ben Gurion University of the Negev, Beer Sheva, Israel
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Goodman C, Podolsky RH, Childers KL, Roberts R, Katz R, Waseem R, Paruchuri A, Stanek J, Berkowitz BA. Do multiple physiological OCT biomarkers indicate age-related decline in rod mitochondrial function in C57BL/6J mice? Front Neurosci 2023; 17:1280453. [PMID: 38046657 PMCID: PMC10693340 DOI: 10.3389/fnins.2023.1280453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 10/31/2023] [Indexed: 12/05/2023] Open
Abstract
Purpose To test the hypothesis that rod photoreceptor mitochondria function in vivo progressively declines over time. Methods 2, 12, and 24 month-old dark- and light-adapted C57BL/6J (B6J) mice were examined by OCT. We measured (i) an index of mitochondrial configuration within photoreceptors measured from the profile shape aspect ratio (MCP/AR) of the hyperreflective band posterior to the external limiting membrane (ELM), (ii) a proxy for energy-dependent pH-triggered water removal, the thickness of the ELM-retinal pigment epithelium (ELM-RPE), and its correlate (iii) the hyporeflective band (HB) signal intensity at the photoreceptor tips. Visual performance was assessed by optokinetic tracking. Results In 2 and 24 month-old mice, MCP/AR in both inferior and superior retina was smaller in light than in dark; no dark-light differences were noted in 12 month-old mice. Dark-adapted inferior and superior, and light-adapted superior, ELM-RPE thickness increased with age. The dark-light difference in ELM-RPE thickness remained constant across all ages. All ages showed a decreased HB signal intensity magnitude in dark relative to light. In 12 month-old mice, the dark-light difference in HB magnitude was greater than in younger and older mice. Anatomically, outer nuclear layer thickness decreased with age. Visual performance indices were reduced at 24 month-old compared to 2 month-old mice. Conclusion While the working hypothesis was not supported herein, the results raise the possibility of a mid-life adaptation in rod mitochondrial function during healthy aging in B6J mice based on OCT biomarkers, a plasticity that occurred prior to declines in visual performance.
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Affiliation(s)
- Cole Goodman
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Robert H. Podolsky
- Biostatistics and Study Methodology, Children’s National Hospital, Silver Spring, MD, United States
| | | | - Robin Roberts
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Ryan Katz
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Rida Waseem
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Anuhya Paruchuri
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Josh Stanek
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Bruce A. Berkowitz
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
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Hardiman W, Clark M, Friel C, Huett A, Pérez-Cota F, Setchfield K, Wright AJ, Tassieri M. Living cells as a biological analog of optical tweezers - a non-invasive microrheology approach. Acta Biomater 2023; 166:317-325. [PMID: 37137402 DOI: 10.1016/j.actbio.2023.04.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 04/14/2023] [Accepted: 04/25/2023] [Indexed: 05/05/2023]
Abstract
Microrheology, the study of fluids on micron length-scales, promises to reveal insights into cellular biology, including mechanical biomarkers of disease and the interplay between biomechanics and cellular function. Here a minimally-invasive passive microrheology technique is applied to individual living cells by chemically binding a bead to the surface of a cell, and observing the mean squared displacement of the bead at timescales ranging from milliseconds to 100s of seconds. Measurements are repeated over the course of hours, and presented alongside analysis to quantify changes in the cells' low-frequency elastic modulus, G0', and the cell's dynamics over the time window ∼10-2 s to 10 s. An analogy to optical trapping allows verification of the invariant viscosity of HeLa S3 cells under control conditions and after cytoskeletal disruption. Stiffening of the cell is observed during cytoskeletal rearrangement in the control case, and cell softening when the actin cytoskeleton is disrupted by Latrunculin B. These data correlate with conventional understanding that integrin binding and recruitment triggers cytoskeletal rearrangement. This is, to our knowledge, the first time that cell stiffening has been measured during focal adhesion maturation, and the longest time over which such stiffening has been quantified by any means. STATEMENT OF SIGNIFICANCE: Here, we present an approach for studying mechanical properties of live cells without applying external forces or inserting tracers. Regulation of cellular biomechanics is crucial to healthy cell function. For the first time in literature, we can non-invasively and passively quantify cell mechanics during interactions with functionalised surface. Our method can monitor the maturation of adhesion sites on the surface of individual live cells without disrupting the cell mechanics by applying forces to the cell. We observe a stiffening response in cells over tens of minutes after a bead chemically binds. This stiffening reduces the deformation rate of the cytoskeleton, although the internal force generation increases. Our method has potential for applications to study mechanics during cell-surface and cell-vesicle interactions.
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Affiliation(s)
- William Hardiman
- Optics and Photonics Research Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK.
| | - Matt Clark
- Optics and Photonics Research Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK
| | - Claire Friel
- School of Life Sciences, University of Nottingham, Medical School, QMC, Nottingham NG7 2UH, UK
| | - Alan Huett
- School of Life Sciences, University of Nottingham, Medical School, QMC, Nottingham NG7 2UH, UK
| | - Fernando Pérez-Cota
- Optics and Photonics Research Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK
| | - Kerry Setchfield
- Optics and Photonics Research Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK
| | - Amanda J Wright
- Optics and Photonics Research Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK.
| | - Manlio Tassieri
- Division of Biomedical Engineering, James Watt School of Engineering, University of Glasgow, Glasgow, G12 8LT, UK.
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Perillo MA, Burgos I, Clop EM, Sanchez JM, Nolan V. The role of water in reactions catalysed by hydrolases under conditions of molecular crowding. Biophys Rev 2023; 15:639-660. [PMID: 37681097 PMCID: PMC10480385 DOI: 10.1007/s12551-023-01104-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 07/23/2023] [Indexed: 09/09/2023] Open
Abstract
Under macromolecular crowding (MC) conditions such as cellular, extracellular, food and other environments of biotechnological interest, the thermodynamic activity of the different macromolecules present in the system is several orders of magnitude higher than in dilute solutions. In this state, the diffusion rates are affected by the volume exclusion induced by the crowders. Immiscible liquid phases, which may arise in MC by liquid-liquid phase separation, may induce a dynamic confinement of reactants, products and/or enzymes, tuning reaction rates. In cellular environments and other crowding conditions, membranes and macromolecules provide, on the whole, large surfaces that can perturb the solvent, causing its immobilisation by adsorption in the short range and also affecting the solvent viscosity in the long range. The latter phenomenon can affect the conformation of a protein and/or the degree of association of its protomers and, consequently, its activity. Changes in the water structure can also alter the enzyme-substrate interaction, and, in the case of hydrolytic enzymes, where water is one of the substrates, it also affects the reaction mechanism. Here, we review the evidence for how macromolecular crowding affects the catalysis induced by hydrolytic enzymes, focusing on the structure and dynamics of water.
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Affiliation(s)
- Maria A. Perillo
- Facultad de Ciencias Exactas, Físicas y Naturales, ICTA and Departamento de Química, Cátedra de Química Biológica, Universidad Nacional de Córdoba, Av. Vélez Sársfield 1611, 5016 Córdoba, Argentina
- CONICET, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), Córdoba, Argentina
| | - Inés Burgos
- CONICET, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), Córdoba, Argentina
- Facultad de Ciencias Exactas, Físicas y Naturales, ICTA and Departamento de Química Industrial y Aplicada, Cátedra de Química Biológica, Universidad Nacional de Córdoba, Av. Vélez Sársfield 1611, 5016 Córdoba, Argentina
| | - Eduardo M. Clop
- Facultad de Ciencias Exactas, Físicas y Naturales, ICTA and Departamento de Química, Cátedra de Química Biológica, Universidad Nacional de Córdoba, Av. Vélez Sársfield 1611, 5016 Córdoba, Argentina
- CONICET, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), Córdoba, Argentina
| | - Julieta M. Sanchez
- Facultad de Ciencias Exactas, Físicas y Naturales, ICTA and Departamento de Química, Cátedra de Química Biológica, Universidad Nacional de Córdoba, Av. Vélez Sársfield 1611, 5016 Córdoba, Argentina
- CONICET, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), Córdoba, Argentina
- Institut de Biotecnologia I de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
- Departament de Genètica I de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
- CIBER de Bioingeniería Biomateriales y Nanomedicina (CIBER-BBN), Bellaterra, 08193 Barcelona, Spain
| | - Verónica Nolan
- Facultad de Ciencias Exactas, Físicas y Naturales, ICTA and Departamento de Química, Cátedra de Química Biológica, Universidad Nacional de Córdoba, Av. Vélez Sársfield 1611, 5016 Córdoba, Argentina
- CONICET, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), Córdoba, Argentina
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Gao S, Li Y, Bissig D, Cohen ED, Podolsky RH, Childers KL, Vernon G, Chen S, Berkowitz BA, Qian H. Functional regulation of an outer retina hyporeflective band on optical coherence tomography images. Sci Rep 2021; 11:10260. [PMID: 33986362 PMCID: PMC8119672 DOI: 10.1038/s41598-021-89599-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/27/2021] [Indexed: 12/30/2022] Open
Abstract
Human and animal retinal optical coherence tomography (OCT) images show a hyporeflective band (HB) between the photoreceptor tip and retinal pigment epithelium layers whose mechanisms are unclear. In mice, HB magnitude and the external limiting membrane-retinal pigment epithelium (ELM-RPE) thickness appear to be dependent on light exposure, which is known to alter photoreceptor mitochondria respiration. Here, we test the hypothesis that these two OCT biomarkers are linked to metabolic activity of the retina. Acetazolamide, which acidifies the subretinal space, had no significant impact on HB magnitude but produced ELM-RPE thinning. Mitochondrial stimulation with 2,4-dinitrophenol reduced both HB magnitude and ELM-RPE thickness in parallel, and also reduced F-actin expression in the same retinal region, but without altering ERG responses. For mice strains with relatively lower (C57BL/6J) or higher (129S6/ev) rod mitochondrial efficacy, light-induced changes in HB magnitude and ELM-RPE thickness were correlated. Humans, analyzed from published data captured with a different protocol, showed a similar light–dark change pattern in HB magnitude as in the mice. Our results indicate that mitochondrial respiration underlies changes in HB magnitude upstream of the pH-sensitive ELM-RPE thickness response. These two distinct OCT biomarkers could be useful indices for non-invasively evaluating photoreceptor mitochondrial metabolic activity.
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Affiliation(s)
- Shasha Gao
- Department of Ophthalmology, the First Affiliated Hospital, Zhengzhou University, Zhengzhou, China.,Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yichao Li
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - David Bissig
- Department of Neurology, University of California Davis, Sacramento, CA, USA
| | - Ethan D Cohen
- Division of Biomedical Physics, Office of Science and Engineering Labs, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD, USA
| | - Robert H Podolsky
- Beaumont Research Institute, Beaumont Health, Royal Oak, MI, 48073, USA
| | | | - Gregory Vernon
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Sonia Chen
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Bruce A Berkowitz
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, USA
| | - Haohua Qian
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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Marques MPM, Batista de Carvalho ALM, Mamede AP, Rudić S, Dopplapudi A, García Sakai V, Batista de Carvalho LAE. Intracellular water as a mediator of anticancer drug action. INT REV PHYS CHEM 2020. [DOI: 10.1080/0144235x.2020.1700083] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- M. P. M. Marques
- Unidade de I&D Química-Física Molecular, Department of Chemistry, University of Coimbra, Coimbra, Portugal
- Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | | | - A. P. Mamede
- Unidade de I&D Química-Física Molecular, Department of Chemistry, University of Coimbra, Coimbra, Portugal
| | - S. Rudić
- STFC Rutherford Appleton Laboratory, ISIS Facility, Chilton, Didcot, UK
| | - A. Dopplapudi
- STFC Rutherford Appleton Laboratory, ISIS Facility, Chilton, Didcot, UK
| | - V. García Sakai
- STFC Rutherford Appleton Laboratory, ISIS Facility, Chilton, Didcot, UK
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Anghelina M, Butt O, Moldovan L, Petrache HI, Moldovan NI. Solvent isotope effect on leukocytes disintegration after large mechanical deformations. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/aafd0f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Maccarini M, Watkins EB, Stidder B, Alcaraz JP, Cornell BA, Martin DK. Nanostructural determination of a lipid bilayer tethered to a gold substrate. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2016; 39:123. [PMID: 27966072 DOI: 10.1140/epje/i2016-16123-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 11/23/2016] [Indexed: 06/06/2023]
Abstract
Tethered lipid bilayer membranes (tBLM) are planar membranes composed of free lipids and molecules tethered to a solid planar substrate providing a useful model of biological membranes for a wide range of biophysical studies and biotechnological applications. The properties of the tBLM depend on the free lipids and on the chemistry of the tethering molecules. We present a nanoscale characterization of a tBLM composed of deuterated 1,2-dimyristoyl-sn-glycero-3-phosphocholine (d-DMPC) free lipids, benzyl disulfide undecaethylene glycol phytanol (DLP) tethering molecules, and benzyl disulfiide tetraethylene glycol polar spacer molecules (PSM) used to control the areal density of tethering molecules through coadsorption. The use of selected isotopic substitution provides a way to distinguish the conformation and location of the tethered lipids from the free lipids and to elucidate how the two components influence the structure of the tBLM. These findings provide useful information to optimise the insertion of transmembrane proteins into the tethered bilayer system.
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Affiliation(s)
- Marco Maccarini
- TIMC/IMAG, Université Grenoble Alpes, (UMR 5525), Grenoble, France.
| | - Erik B Watkins
- Los Alamos National Laboratory, 87545, Los Alamos, NM, USA
| | - Barry Stidder
- TIMC/IMAG, Université Grenoble Alpes, (UMR 5525), Grenoble, France
| | | | - Bruce A Cornell
- SDx Tethered Membranes Pty Ltd u6 30-32, Barcoo Street, 2069, Roseville, NSW, Australia
| | - Donald K Martin
- TIMC/IMAG, Université Grenoble Alpes, (UMR 5525), Grenoble, France
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Maloney JM, Van Vliet KJ. Chemoenvironmental modulators of fluidity in the suspended biological cell. SOFT MATTER 2014; 10:8031-8042. [PMID: 25160132 DOI: 10.1039/c4sm00743c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Biological cells can be characterized as "soft matter" with mechanical characteristics potentially modulated by external cues such as pharmaceutical dosage or fever temperature. Further, quantifying the effects of chemical and physical stimuli on a cell's mechanical response informs models of living cells as complex materials. Here, we investigate the mechanical behavior of single biological cells in terms of fluidity, or mechanical hysteresivity normalized to the extremes of an elastic solid or a viscous liquid. This parameter, which complements stiffness when describing whole-cell viscoelastic response, can be determined for a suspended cell within subsecond times. Questions remain, however, about the origin of fluidity as a conserved parameter across timescales, the physical interpretation of its magnitude, and its potential use for high-throughput sorting and separation of interesting cells by mechanical means. Therefore, we exposed suspended CH27 lymphoma cells to various chemoenvironmental conditions--temperature, pharmacological agents, pH, and osmolarity--and measured cell fluidity with a non-contact technique to extend familiarity with suspended-cell mechanics in the context of both soft-matter physics and mechanical flow cytometry development. The actin-cytoskeleton-disassembling drug latrunculin exacted a large effect on mechanical behavior, amenable to dose-dependence analysis of coupled changes in fluidity and stiffness. Fluidity was minimally affected by pH changes from 6.5 to 8.5, but strongly modulated by osmotic challenge to the cell, where the range spanned halfway from solid to liquid behavior. Together, these results support the interpretation of fluidity as a reciprocal friction within the actin cytoskeleton, with implications both for cytoskeletal models and for expectations when separating interesting cell subpopulations by mechanical means in the suspended state.
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Affiliation(s)
- John M Maloney
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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