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Mahadeva M, Niestępski S, Kowacz M. Dependence of cell's membrane potential on extracellular voltage observed in Chara globularis. Biophys Chem 2024; 307:107199. [PMID: 38335807 DOI: 10.1016/j.bpc.2024.107199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 01/31/2024] [Accepted: 02/04/2024] [Indexed: 02/12/2024]
Abstract
The membrane potential (Vm) of a cell results from the selective movement of ions across the cell membrane. Recent studies have revealed the presence of a gradient of voltage within a few nanometers adjacent to erythrocytes. Very notably this voltage is modified in response to changes in cell's membrane potential thus effectively extending the potential beyond the membrane and into the solution. In this study, using the microelectrode technique, we provide experimental evidence for the existence of a gradient of negative extracellular voltage (Vz) in a wide zone close to the cell wall of algal cells, extending over several micrometers. Modulating the ionic concentration of the extracellular solution with CO2 alters the extracellular voltage and causes an immediate change in Vm. Elevated extracellular CO2 levels depolarize the cell and hyperpolarize the zone of extracellular voltage (ZEV) by the same magnitude. This observation strongly suggests a coupling effect between Vz and Vm. An increase in the level of intracellular CO2 (dark respiration) leads to hyperpolarization of the cell without any immediate effect on the extracellular voltage. Therefore, the metabolic activity of a cell can proceed without inducing changes in Vz. Conversely, Vz can be modified by external stimulation without metabolic input from the cell. The evolution of the ZEV, particularly around spines and wounded cells, where ion exchange is enhanced, suggests that the formation of the ZEV may be attributed to the exchange of ions across the cell wall and cell membrane. By comparing the changes in Vm in response to external stimuli, as measured by electrodes and observed using a potential-sensitive dye, we provide experimental evidence demonstrating the significance of extracellular voltage in determining the cell's membrane potential. This may have implications for our understanding of cell membrane potential generation beyond the activities of ion channels.
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Affiliation(s)
- Manohara Mahadeva
- Department of Reproductive Immunology & Pathology, Institute of Animal Reproduction and Food Research Polish Academy of Sciences, 10-748 Olsztyn, Poland
| | - Sebastian Niestępski
- Department of Reproductive Immunology & Pathology, Institute of Animal Reproduction and Food Research Polish Academy of Sciences, 10-748 Olsztyn, Poland
| | - Magdalena Kowacz
- Department of Reproductive Immunology & Pathology, Institute of Animal Reproduction and Food Research Polish Academy of Sciences, 10-748 Olsztyn, Poland.
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2
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Socas LBP, Ambroggio EE. Linking surface tension to water polarization with a new hypothesis: The Ling-Damodaran Isotherm. Colloids Surf B Biointerfaces 2023; 230:113515. [PMID: 37634284 DOI: 10.1016/j.colsurfb.2023.113515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 08/08/2023] [Accepted: 08/11/2023] [Indexed: 08/29/2023]
Abstract
Studying aqueous solutions of complex (bio)polymers is essential from both theoretical and practical perspectives. To understand the principles that govern the properties of these solutions is pivotal for the study of biological processes, considering that the most distinguished components of the cells are polymers (proteins, nucleic acids). These macromolecular aqueous systems, known as colloids, has raise the interest of scientists in recent years. It is known that several physicochemical properties deviate from ideal behaviour in this kind of solutions and that the physical state of water is different compared to its pure state. Particularly, the surface tension of such mixtures often shows a peculiar profile at semi-dilute and concentrated conditions. Here, we joined the colloidal concept of water polarization (proposed in the Association-Induction Hypothesis) with Damodaran's formalism for surface tension to theoretically derive a compelling mathematical model that explains the behaviour of polymer solutions. We measured the surface tension and osmolarity of different polyethylene oxide solutions and we used the ACDAN fluorescence probe to assess the water dipolar relaxation (polarization) in these mixtures. As a proof of concept, we also studied the influence of these polymer solutions on lipid interfaces. Our isotherm model explains the experimental observations with a unifying view that correlates with other measured properties, such as osmolarity and water dipolar relaxation. This provides a link between interfacial and bulk physicochemical properties of polymer solutions, also giving a new framework for studying the interaction of colloidal systems with lipid membranes interfaces.
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Affiliation(s)
- L B P Socas
- Universidad Nacional de Córdoba, Facultad de Ciencias Químicas, Departamento de Química Biológica-Ranwel Caputto, Haya de la Torre y Medina Allende s/n, Córdoba X5000HUA, Argentina; CONICET, Universidad Nacional de Córdoba, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Haya de la Torre y Medina Allende s/n, Córdoba X5000HUA, Argentina.
| | - E E Ambroggio
- Universidad Nacional de Córdoba, Facultad de Ciencias Químicas, Departamento de Química Biológica-Ranwel Caputto, Haya de la Torre y Medina Allende s/n, Córdoba X5000HUA, Argentina; CONICET, Universidad Nacional de Córdoba, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Haya de la Torre y Medina Allende s/n, Córdoba X5000HUA, Argentina.
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3
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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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Abstract
Recent years have seen substantial efforts aimed at constructing artificial cells from various molecular components with the aim of mimicking the processes, behaviours and architectures found in biological systems. Artificial cell development ultimately aims to produce model constructs that progress our understanding of biology, as well as forming the basis for functional bio-inspired devices that can be used in fields such as therapeutic delivery, biosensing, cell therapy and bioremediation. Typically, artificial cells rely on a bilayer membrane chassis and have fluid aqueous interiors to mimic biological cells. However, a desire to more accurately replicate the gel-like properties of intracellular and extracellular biological environments has driven increasing efforts to build cell mimics based on hydrogels. This has enabled researchers to exploit some of the unique functional properties of hydrogels that have seen them deployed in fields such as tissue engineering, biomaterials and drug delivery. In this Review, we explore how hydrogels can be leveraged in the context of artificial cell development. We also discuss how hydrogels can potentially be incorporated within the next generation of artificial cells to engineer improved biological mimics and functional microsystems.
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Tang B, Liu BH, Liu ZY, Luo MY, Shi XH, Pang DW. Quantum Dots with a Compact Amphiphilic Zwitterionic Coating. ACS APPLIED MATERIALS & INTERFACES 2022; 14:28097-28104. [PMID: 35686447 DOI: 10.1021/acsami.2c04438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Generally speaking, it is difficult to keep nanomaterials encapsulated in amphiphilic polymers like octylamine-grafted poly(acrylic acid) (OPA) compact in coating-layer, with a small hydrodynamic size. Here, we prepared stable hydrophilic quantum dots (QDs) via encapsulation in ∼3 nm-long amphiphilic and zwitterionic (AZ) molecules. After encapsulation with AZ molecules, the coated QDs are only 2.1 nm thicker in coating, instead of 5.4 nm with OPA. Meanwhile, the hydrodynamic sizes of CdSe/CdS, ZnCdSeS, ZnCdSe/ZnS, and CdSe/ZnS QDs encapsulated in AZ molecules (AZ-QDs) are less than 15 nm, and 6-7 nm smaller than those of QDs in OPA (OPA-QDs). Notably, both extracellular and intracellular nonspecific binding of AZ-QDs is approximately 100-folds lower than that of OPA-QDs.
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Affiliation(s)
- Bo Tang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China
| | - Bing-Hua Liu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China
| | - Zhen-Ya Liu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China
| | - Meng-Yao Luo
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China
| | - Xue-Hui Shi
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Center for New Organic Matter, Research Center for Analytical Sciences, College of Chemistry, Frontiers Science Center for Cell Responses, Nankai University, Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300071, P. R. China
| | - Dai-Wen Pang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Center for New Organic Matter, Research Center for Analytical Sciences, College of Chemistry, Frontiers Science Center for Cell Responses, Nankai University, Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300071, P. R. China
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6
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Vorontsova I, Vallmitjana A, Torrado B, Schilling TF, Hall JE, Gratton E, Malacrida L. In vivo macromolecular crowding is differentially modulated by aquaporin 0 in zebrafish lens: Insights from a nanoenvironment sensor and spectral imaging. SCIENCE ADVANCES 2022; 8:eabj4833. [PMID: 35171678 PMCID: PMC8849302 DOI: 10.1126/sciadv.abj4833] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 12/23/2021] [Indexed: 05/14/2023]
Abstract
Macromolecular crowding is crucial for cellular homeostasis. In vivo studies of macromolecular crowding and water dynamics are needed to understand their roles in cellular physiology and fate determination. Macromolecular crowding in the lens is essential for normal optics, and an understanding of its regulation will help prevent cataract and presbyopia. Here, we combine the use of the nanoenvironmental sensor [6-acetyl-2-dimethylaminonaphthalene (ACDAN)] to visualize lens macromolecular crowding with in vivo studies of aquaporin 0 zebrafish mutants that disrupt its regulation. Spectral phasor analysis of ACDAN fluorescence reveals water dipolar relaxation and demonstrates that mutations in two zebrafish aquaporin 0s, Aqp0a and Aqp0b, alter water state and macromolecular crowding in living lenses. Our results provide in vivo evidence that Aqp0a promotes fluid influx in the deeper lens cortex, whereas Aqp0b facilitates fluid efflux. This evidence reveals previously unidentified spatial regulation of macromolecular crowding and spatially distinct roles for Aqp0 in the lens.
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Affiliation(s)
- Irene Vorontsova
- Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
- Developmental and Cell Biology, University of California, Irvine, Irvine, CA, USA
- Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA
| | | | - Belén Torrado
- Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | - Thomas F. Schilling
- Developmental and Cell Biology, University of California, Irvine, Irvine, CA, USA
| | - James E. Hall
- Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Enrico Gratton
- Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | - Leonel Malacrida
- Departamento de Fisiopatología, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
- Advanced Bioimaging Unit, Institut Pasteur of Montevideo and Universidad de la República, Montevideo, Uruguay
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7
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CynthiaVanegas-Villa S, Milena Torres-Cifuentes D, Baylon-Pacheco L, Espíritu-Gordillo P, Durán-Díaz Á, Luis Rosales-Encina J, Omaña-Molina M. External pH Variations Modify Proliferation, Erythrophagocytosis, Cytoskeleton Remodeling, and Cell Morphology of Entamoeba histolytica Trophozoites. Protist 2022; 173:125857. [DOI: 10.1016/j.protis.2022.125857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 10/19/2022]
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8
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Lee MS, Kim GR, Kim SS, Lee JK, Kim W, Kwak JH, Kil SH, Kim GD. Histological and impedance changes of skeletal muscle by whole-body critical irradiation in a rat model. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2022; 30:697-708. [PMID: 35466920 DOI: 10.3233/xst-211122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this study, the electrical resistance of the whole body and histological changes of skeletal muscle were investigated in rats according to the increase in radiation dose. A total of 15 male Sprague-Dawley rats (5-weeks-old) were randomly divided into 5 groups (each, n = 3). Each group received 1 Gy, 5 Gy, 10 Gy and 20 Gy systemic exposure, and the non-irradiated group was used as a control for morphological comparison. After attaching an electrode clip to the forelimb of the rat, an AC frequency was applied before and 4 days after irradiation using an impedance/gain-phase analyzer, and the measurement system was automatically controlled with LabVIEW. Comparing to before irradiation after 4 days, the difference in the average impedance values at 1 Gy, 5 Gy, 10 Gy, and 20 Gy was 1188±989 ohm, 3076±2251 ohm, 7650±6836 ohm, and 10478±6250 ohm, respectively. By comparing the normal group and the experimental group, muscle fiber atrophy and collagen fibers around blood vessels were observed (p < 0.05, control group vs 5 Gy or more high-dose group). These results confirmed the previously reported morphological changes of skeletal muscle and our hypothesis that whole-body impedance measurement enables to reflect tissue changes after irradiation.
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Affiliation(s)
- Moo Seok Lee
- Department of Nuclear Medicine, Pusan National University Hospital, Busan, Korea
| | - Gyeong Rip Kim
- Department of Neurosurgery, Pusan National University Yang-san Hospital, Yang-san, Korea
| | - Sang Sik Kim
- Electron Microscope Laboratory, Biomedical Research Institute, Pusan National University Hospital, Busan, Korea
| | - Jong Kyu Lee
- Department of Physics, Pukyong National University, Busan, Korea
| | - Wontaek Kim
- Department of Radiation Oncology, Pusan National University, Busan, Korea
| | - Jong Hyeok Kwak
- Department of Radiology, Pusan National University Yang-san Hospital, Yangsan, Korea
| | - Sang Hyeong Kil
- Department of Nuclear Medicine, Pusan National University Yang-san Hospital, Yang-san, Korea
| | - Gun Do Kim
- Department of Microbiology, Pukyong National University, Busan, Korea
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9
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Esteki MH, Malandrino A, Alemrajabi AA, Sheridan GK, Charras G, Moeendarbary E. Poroelastic osmoregulation of living cell volume. iScience 2021; 24:103482. [PMID: 34927026 PMCID: PMC8649806 DOI: 10.1016/j.isci.2021.103482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 08/19/2021] [Accepted: 11/19/2021] [Indexed: 11/22/2022] Open
Abstract
Cells maintain their volume through fine intracellular osmolarity regulation. Osmotic challenges drive fluid into or out of cells causing swelling or shrinkage, respectively. The dynamics of cell volume changes depending on the rheology of the cellular constituents and on how fast the fluid permeates through the membrane and cytoplasm. We investigated whether and how poroelasticity can describe volume dynamics in response to osmotic shocks. We exposed cells to osmotic perturbations and used defocusing epifluorescence microscopy on membrane-attached fluorescent nanospheres to track volume dynamics with high spatiotemporal resolution. We found that a poroelastic model that considers both geometrical and pressurization rates captures fluid-cytoskeleton interactions, which are rate-limiting factors in controlling volume changes at short timescales. Linking cellular responses to osmotic shocks and cell mechanics through poroelasticity can predict the cell state in health, disease, or in response to novel therapeutics. Cell height changes can be finely captured by defocusing microscopy Water permeation and cellular deformability regulate dynamics of cell volume changes Poroelasticity describes the dynamics of cell volume changes The response of cell to hypo or hyperosmotic shocks are modeled by poroelasticity
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Affiliation(s)
- Mohammad Hadi Esteki
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran.,Department of Mechanical Engineering, University College London, London, UK
| | - Andrea Malandrino
- Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Engineering, Universitat Politècnica de Catalunya, Barcelona, Spain
| | - Ali Akbar Alemrajabi
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
| | - Graham K Sheridan
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, UK
| | - Guillaume Charras
- London Centre for Nanotechnology, University College London, London, UK.,Department of Cell and Developmental Biology, University College London, London, UK.,Institute for the Physics of Living Systems, University College London, London, UK
| | - Emad Moeendarbary
- Department of Mechanical Engineering, University College London, London, UK.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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10
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Dual-modified nanoparticles overcome sequential absorption barriers for oral insulin delivery. J Control Release 2021; 342:1-13. [PMID: 34864116 DOI: 10.1016/j.jconrel.2021.11.045] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 11/24/2021] [Accepted: 11/29/2021] [Indexed: 01/25/2023]
Abstract
The efficacy of oral insulin drug delivery is seriously hampered by multiple gastrointestinal barriers, especially transepithelial barriers, including apical endocytosis, lysosomal degradation, cytosolic diffusion and basolateral exocytosis. In this study, a functional nanoparticle (PG-FAPEP) with dual-modification was constructed to sequentially address these important absorption obstacles for improved oral insulin delivery. The dual surface decorations folate and charge-convertible tripeptide endowed PG-FAPEP with the ability to target the apical and basolateral sides of enterocytes, respectively. After fast diffusion across the mucus layer, PG-FAPEP could be efficiently internalized into epithelial cells via a folate receptor-mediated pathway and subsequently became positively charged in acidic lysosomes due to the surface tripeptide, triggering the proton sponge effect to escape lysosomes. When entering the cytosolic medium, PG-FAPEP was converted to neutral charge again, attenuating intracellular adhesion, and gained improved motility toward the basolateral side. Finally, the tripeptide helped PG-FAPEP recognize the proton-coupled oligopeptide transporter (PHT1) in the basolateral membrane, boosting intact exocytosis across intestinal epithelial cells. The in vivo studies further verified that PG-FAPEP could traverse the intestinal epithelium by folate receptor-mediated endocytosis, lysosomal escape, and PHT1-mediated exocytosis, exhibiting a high oral insulin bioavailability of 14.3% and a prolonged hypoglycemic effect. This formulation addresses multiple absorption barriers on demand with a simple dual-modification strategy. Therefore, these features allow PG-FAPEP to unleash the potential of oral macromolecule delivery.
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11
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Sanchez Noriega JL, Chartrand NA, Valdoz JC, Cribbs CG, Jacobs DA, Poulson D, Viglione MS, Woolley AT, Van Ry PM, Christensen KA, Nordin GP. Spatially and optically tailored 3D printing for highly miniaturized and integrated microfluidics. Nat Commun 2021; 12:5509. [PMID: 34535656 PMCID: PMC8448845 DOI: 10.1038/s41467-021-25788-w] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 08/31/2021] [Indexed: 02/07/2023] Open
Abstract
Traditional 3D printing based on Digital Light Processing Stereolithography (DLP-SL) is unnecessarily limiting as applied to microfluidic device fabrication, especially for high-resolution features. This limitation is due primarily to inherent tradeoffs between layer thickness, exposure time, material strength, and optical penetration that can be impossible to satisfy for microfluidic features. We introduce a generalized 3D printing process that significantly expands the accessible spatially distributed optical dose parameter space to enable the fabrication of much higher resolution 3D components without increasing the resolution of the 3D printer. Here we demonstrate component miniaturization in conjunction with a high degree of integration, including 15 μm × 15 μm valves and a 2.2 mm × 1.1 mm 10-stage 2-fold serial diluter. These results illustrate our approach's promise to enable highly functional and compact microfluidic devices for a wide variety of biomolecular applications.
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Affiliation(s)
- Jose L Sanchez Noriega
- Electrical and Computer Engineering Department, Brigham Young University, Provo, UT, 84602, USA
| | - Nicholas A Chartrand
- Chemistry and Biochemistry Department, Brigham Young University, Provo, UT, 84602, USA
| | - Jonard Corpuz Valdoz
- Chemistry and Biochemistry Department, Brigham Young University, Provo, UT, 84602, USA
| | - Collin G Cribbs
- Chemistry and Biochemistry Department, Brigham Young University, Provo, UT, 84602, USA
| | - Dallin A Jacobs
- Chemistry and Biochemistry Department, Brigham Young University, Provo, UT, 84602, USA
| | - Daniel Poulson
- Chemistry and Biochemistry Department, Brigham Young University, Provo, UT, 84602, USA
| | - Matthew S Viglione
- Electrical and Computer Engineering Department, Brigham Young University, Provo, UT, 84602, USA
| | - Adam T Woolley
- Chemistry and Biochemistry Department, Brigham Young University, Provo, UT, 84602, USA
| | - Pam M Van Ry
- Chemistry and Biochemistry Department, Brigham Young University, Provo, UT, 84602, USA
| | - Kenneth A Christensen
- Chemistry and Biochemistry Department, Brigham Young University, Provo, UT, 84602, USA
| | - Gregory P Nordin
- Electrical and Computer Engineering Department, Brigham Young University, Provo, UT, 84602, USA.
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12
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Galera-Laporta L, Comerci CJ, Garcia-Ojalvo J, Süel GM. IonoBiology: The functional dynamics of the intracellular metallome, with lessons from bacteria. Cell Syst 2021; 12:497-508. [PMID: 34139162 PMCID: PMC8570674 DOI: 10.1016/j.cels.2021.04.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/16/2021] [Accepted: 04/28/2021] [Indexed: 12/29/2022]
Abstract
Metal ions are essential for life and represent the second most abundant constituent (after water) of any living cell. While the biological importance of inorganic ions has been appreciated for over a century, we are far from a comprehensive understanding of the functional roles that ions play in cells and organisms. In particular, recent advances are challenging the traditional view that cells maintain constant levels of ion concentrations (ion homeostasis). In fact, the ionic composition (metallome) of cells appears to be purposefully dynamic. The scientific journey that started over 60 years ago with the seminal work by Hodgkin and Huxley on action potentials in neurons is far from reaching its end. New evidence is uncovering how changes in ionic composition regulate unexpected cellular functions and physiology, especially in bacteria, thereby hinting at the evolutionary origins of the dynamic metallome. It is an exciting time for this field of biology, which we discuss and refer to here as IonoBiology.
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Affiliation(s)
- Leticia Galera-Laporta
- Molecular Biology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Colin J Comerci
- Molecular Biology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jordi Garcia-Ojalvo
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona 08003, Spain
| | - Gürol M Süel
- Molecular Biology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA; San Diego Center for Systems Biology, University of California, San Diego, La Jolla, CA 92093- 0380, USA; Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093-0380, USA.
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13
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Fajrial AK, Liu K, Gao Y, Gu J, Lakerveld R, Ding X. Characterization of Single-Cell Osmotic Swelling Dynamics for New Physical Biomarkers. Anal Chem 2021; 93:1317-1325. [PMID: 33253534 DOI: 10.1021/acs.analchem.0c02289] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Characterization of cell physical biomarkers is vital to understand cell properties and applicable for disease diagnostics. Current methods used to analyze physical phenotypes involve external forces to deform the cells. Alternatively, internal tension forces via osmotic swelling can also deform the cells. However, an established assumption contends that the forces generated during hypotonic swelling concentrated on the plasma membrane are incapable of assessing the physical properties of nucleated cells. Here, we utilized an osmotic swelling approach to characterize different types of nucleated cells. Using a microfluidic device for cell trapping arrays with truncated hanging micropillars (CellHangars), we isolated single cells and evaluated the swelling dynamics during the hypotonic challenge at 1 s time resolution. We demonstrated that cells with different mechanical phenotypes showed unique swelling dynamics signature. Different types of cells can be classified with an accuracy of up to ∼99%. We also showed that swelling dynamics can detect cellular mechanical property changes due to cytoskeleton disruption. Considering its simplicity, swelling dynamics offers an invaluable label-free physical biomarker for cells with potential applications in both biological studies and clinical practice.
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Affiliation(s)
- Apresio K Fajrial
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, UCB 427, Boulder, Colorado 80309, United States
| | - Kun Liu
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, UCB 427, Boulder, Colorado 80309, United States
| | - Yu Gao
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, UCB 427, Boulder, Colorado 80309, United States
| | - Junhao Gu
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Richard Lakerveld
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xiaoyun Ding
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, UCB 427, Boulder, Colorado 80309, United States.,Biomedical Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
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14
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Božič B, Zemljič Jokhadar Š, Kristanc L, Gomišček G. Cell Volume Changes and Membrane Ruptures Induced by Hypotonic Electrolyte and Sugar Solutions. Front Physiol 2020; 11:582781. [PMID: 33364974 PMCID: PMC7750460 DOI: 10.3389/fphys.2020.582781] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 11/06/2020] [Indexed: 01/09/2023] Open
Abstract
The cell volume changes induced by hypotonic electrolyte and sucrose solutions were studied in Chinese-hamster-ovary epithelial cells. The effects in the solutions with osmolarities between 32 and 315 mosM/L and distilled water were analyzed using bright-field and fluorescence confocal microscopy. The changes of the cell volume, accompanied by the detachment of cells, the formation of blebs, and the occurrence of almost spherical vesicle-like cells (“cell-vesicles”), showed significant differences in the long-time responses of the cells in the electrolyte solutions compared with the sucrose-containing solutions. A theoretical model based on different permeabilities of ions and sucrose molecules and on the action of Na+/K+-ATPase pumps is applied. It is consistent with the observed temporal behavior of the cells’ volume and the occurrence of tension-induced membrane ruptures and explains lower long-time responses of the cells in the sucrose solutions.
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Affiliation(s)
- Bojan Božič
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Špela Zemljič Jokhadar
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | - Luka Kristanc
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Gregor Gomišček
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
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15
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Abstract
Suspensions of soft and highly deformable microgels can be concentrated far more than suspensions of hard colloids, leading to their unusual mechanical properties. Microgels can accommodate compression in suspensions in a variety of ways such as interpenetration, deformation, and shrinking. Previous experiments have offered insightful, but somewhat conflicting, accounts of the behavior of individual microgels in compressed suspensions. We develop a mesoscale computational model to probe the behavior of compressed suspensions consisting of microgels with different architectures at a variety of packing fractions and solvent conditions. We find that microgels predominantly change shape and mildly shrink above random close packing. Interpenetration is only appreciable above space filling, remaining small relative to the mean distance between cross-links. At even higher packing fractions, microgels solely shrink. Remarkably, irrespective of the single-microgel properties, and whether the suspension concentration is changed via changing the particle number density or the swelling state of the particles, which can even result in colloidal gelation, the mechanics of the suspension can be quantified in terms of the single-microgel bulk modulus, which thus emerges as the correct mechanical measure for these type of soft-colloidal suspensions. Our results rationalize the many and varied experimental results, providing insights into the relative importance of effects defining the mechanics of suspensions comprising soft particles.
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16
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Kowacz M, Pollack GH. Cells in New Light: Ion Concentration, Voltage, and Pressure Gradients across a Hydrogel Membrane. ACS OMEGA 2020; 5:21024-21031. [PMID: 32875239 PMCID: PMC7450609 DOI: 10.1021/acsomega.0c02595] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 07/27/2020] [Indexed: 06/11/2023]
Abstract
The ionic compositions of the intra- and extracellular environments are distinct from one another, with K+ being the main cation in the cytosol and Na+ being the most abundant cation outside of the cell. Specific ions can permeate into and out of the cell at different rates, bringing about uneven distribution of charges and development of negative electric potential inside the cell. Each healthy cell must maintain a specific ion concentration gradient and voltage. To account for these functions, various ionic pumps and channels located within the cell membrane have been invoked. In this work, we use a porous alginate hydrogel as a model gelatinous network representing the plant cell wall or cytoskeleton of the animal cell. We show that the gel barrier is able to maintain a stable separation of ionic solutions of different ionic strengths and chemical compositions without any pumping activity. For the Na+/K+ concentration gradient sustained across the barrier, a negative electric potential develops within the K+-rich side. The situation is reminiscent of that in the cell. Furthermore, also the advective flow of water molecules across the gel barrier is restricted, despite the gel's large pores and the osmotic or hydrostatic pressure gradients across it. This feature has important implications for osmoregulation. We propose a mechanism in which charge separation and electric fields developing across the permselective (gel) membrane prevent ion and bulk fluid flows ordinarily driven by chemical and pressure gradients.
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17
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Cellular metabolism and colloids: Realistically linking physiology and biological physical chemistry. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 162:79-88. [PMID: 32565181 DOI: 10.1016/j.pbiomolbio.2020.06.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 05/25/2020] [Accepted: 06/02/2020] [Indexed: 11/22/2022]
Abstract
Important concepts from colloidal physical chemistry such as coacervation, phase transitions, emergent properties and ionic association, are currently emerging in the lexicon of cellular biology, prompted mostly by recent experimental observations of liquid phase coexistence in the cell cytosol. Nevertheless, from an historical point of view, the application of these concepts in cell biology is not new. They were key concepts into the so-called protoplasmic doctrine, an alternative (and largely forgotten) approach to cell physiology. The most complete theory originating from this line of thinking was the Association-Induction Hypothesis (AIH), introduced by Gilbert N. Ling in 1962. The AIH, which envisions living cells as complex dynamical colloidal systems, provides ample theory and experimental evidence to call into question the now dominant view of living cells as fluid-filled vesicles. This review attempts to present and discuss the usefulness of the AIH to understand a series of experimental observations from our laboratory from living suspensions of the yeast Saccharomyces cerevisiae exhibiting glycolytic oscillations. Particularly, the AIH helped us integrate, in a mechanistic sense, the basis of a strong temporal coupling observed between ATP and a series of cellular properties such as intracellular water dipolar relaxation, intracellular K+ concentration, among many others, where the colloidal physical chemistry of the cell interior plays a fundamental role.
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18
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Han Z, Sarkar S, Smith AM. Zwitterion and Oligo(ethylene glycol) Synergy Minimizes Nonspecific Binding of Compact Quantum Dots. ACS NANO 2020; 14:3227-3241. [PMID: 32105448 PMCID: PMC7321848 DOI: 10.1021/acsnano.9b08658] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Quantum dots (QDs) are a class of fluorescent nanocrystals in development as labels for molecular imaging in cells and tissues. Recently, coatings for quantum dots based on multidentate polymers have improved labeling performance in a range of bioanalytical applications, primarily due to reduced probe hydrodynamic size. Now, an ongoing challenge is to eliminate nonspecific binding between these small probes and cellular components that mask specifically labeled molecules. Here, we describe insights into controlling and minimizing intermolecular interactions governing nonspecific binding using multidentate polymers with tunable hydrophilic functional groups that are cationic, anionic, zwitterionic (ZW), or nonionic (oligoethylene glycol; OEG). By fixing surface-binding groups and polymer length, coated colloids have similar sizes but diverse physicochemical properties. We measure binding to globular proteins, fixed cells, and living cells and observe a substantial improvement in nonspecific binding resistance when surfaces are functionalized with a combination of ZW and OEG. The independent underlying effects of counterion adsorption and flexibility appear to synergistically resist adsorption when combined, particularly for fixed cells enriched in both charged and hydrophobic moieties. We further show that ZW-OEG QDs are stable under diverse conditions and can be self-assembled with antibodies to specifically label surface antigens on living cells and cytoplasmic proteins in fixed cells. This surface engineering strategy can be adopted across the diverse range of colloidal materials currently in use and in development for biomedical applications to optimize their molecular labeling specificity.
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Affiliation(s)
- Zhiyuan Han
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Suresh Sarkar
- Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Andrew M Smith
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Carle Illinois College of Medicine, Urbana, Illinois 61801, United States
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19
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Heimlicher MB, Bächler M, Liu M, Ibeneche-Nnewihe C, Florin EL, Hoenger A, Brunner D. Reversible solidification of fission yeast cytoplasm after prolonged nutrient starvation. J Cell Sci 2019; 132:jcs.231688. [PMID: 31558680 PMCID: PMC6857596 DOI: 10.1242/jcs.231688] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 09/20/2019] [Indexed: 12/19/2022] Open
Abstract
Cells depend on a highly ordered organisation of their content and must develop strategies to maintain the anisotropic distribution of organelles during periods of nutrient shortage. One of these strategies is to solidify the cytoplasm, which was observed in bacteria and yeast cells with acutely interrupted energy production. Here, we describe a different type of cytoplasm solidification fission yeast cells switch to, after having run out of nutrients during multiple days in culture. It provides the most profound reversible cytoplasmic solidification of yeast cells described to date. Our data exclude the previously proposed mechanisms for cytoplasm solidification in yeasts and suggest a mechanism that immobilises cellular components in a size-dependent manner. We provide experimental evidence that, in addition to time, cells use intrinsic nutrients and energy sources to reach this state. Such cytoplasmic solidification may provide a robust means to protect cellular architecture in dormant cells. Summary: After prolonged quiescence, fission yeast cell populations switch state to immobilise subcellular components much more profoundly than cells experiencing acute energy depletion.
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Affiliation(s)
- Maria B Heimlicher
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Mirjam Bächler
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Minghua Liu
- Dept. of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, UCB-0347, Boulder, CO 80309, USA
| | - Chieze Ibeneche-Nnewihe
- Center for Nonlinear Dynamics and Department of Physics, University of Texas at Austin, Austin, TX 78712, USA
| | - Ernst-Ludwig Florin
- Center for Nonlinear Dynamics and Department of Physics, University of Texas at Austin, Austin, TX 78712, USA
| | - Andreas Hoenger
- Dept. of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, UCB-0347, Boulder, CO 80309, USA
| | - Damian Brunner
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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20
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Bagatolli LA, Stock RP, Olsen LF. Coupled Response of Membrane Hydration with Oscillating Metabolism in Live Cells: An Alternative Way to Modulate Structural Aspects of Biological Membranes? Biomolecules 2019; 9:E687. [PMID: 31684090 PMCID: PMC6921054 DOI: 10.3390/biom9110687] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 10/29/2019] [Accepted: 10/30/2019] [Indexed: 12/12/2022] Open
Abstract
We propose that active metabolic processes may regulate structural changes in biological membranes via the physical state of cell water. This proposition is based on recent results obtained from our group in yeast cells displaying glycolytic oscillations, where we demonstrated that there is a tight coupling between the oscillatory behavior of glycolytic metabolites (ATP, NADH) and the extent of the dipolar relaxation of intracellular water, which oscillates synchronously. The mechanism we suggest involves the active participation of a polarized intracellular water network whose degree of polarization is dynamically modulated by temporal ATP fluctuations caused by metabolism with intervention of a functional cytoskeleton, as conceived in the long overlooked association-induction hypothesis (AIH) of Gilbert Ling. Our results show that the polarized state of intracellular water can be propagated from the cytosol to regions containing membranes. Since changes in the extent of the polarization of water impinge on its chemical activity, we hypothesize that metabolism dynamically controls the local structure of cellular membranes via lyotropic effects. This hypothesis offers an alternative way to interpret membrane related phenomena (e.g., changes in local curvature pertinent to endo/exocytosis or dynamical changes in membranous organelle structure, among others) by integrating relevant but mostly overlooked physicochemical characteristics of the cellular milieu.
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Affiliation(s)
- Luis A Bagatolli
- Instituto de Investigación Médica Mercedes y Martín Ferreyra-INIMEC (CONICET)-Universidad Nacional de Córdoba, Friuli 2434, Córdoba 5016, Argentina.
- Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina.
| | - Roberto P Stock
- MEMPHYS-International and Interdisciplinary Research Network, 5230 Odense, Denmark.
| | - Lars F Olsen
- University of Southern Denmark, Institute for Biochemistry and Molecular Biology, Campusvej 55, 5230 Odense, Denmark.
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21
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Sharma A, Smith HJ, Yao P, Mair WB. Causal roles of mitochondrial dynamics in longevity and healthy aging. EMBO Rep 2019; 20:e48395. [PMID: 31667999 DOI: 10.15252/embr.201948395] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 07/24/2019] [Accepted: 10/09/2019] [Indexed: 12/14/2022] Open
Abstract
Mitochondria are organized in the cell in the form of a dynamic, interconnected network. Mitochondrial dynamics, regulated by mitochondrial fission, fusion, and trafficking, ensure restructuring of this complex reticulum in response to nutrient availability, molecular signals, and cellular stress. Aberrant mitochondrial structures have long been observed in aging and age-related diseases indicating that mitochondrial dynamics are compromised as cells age. However, the specific mechanisms by which aging affects mitochondrial dynamics and whether these changes are causally or casually associated with cellular and organismal aging is not clear. Here, we review recent studies that show specifically how mitochondrial fission, fusion, and trafficking are altered with age. We discuss factors that change with age to directly or indirectly influence mitochondrial dynamics while examining causal roles for altered mitochondrial dynamics in healthy aging and underlying functional outputs that might affect longevity. Lastly, we propose that altered mitochondrial dynamics might not just be a passive consequence of aging but might constitute an adaptive mechanism to mitigate age-dependent cellular impairments and might be targeted to increase longevity and promote healthy aging.
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Affiliation(s)
- Arpit Sharma
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Hannah J Smith
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Pallas Yao
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - William B Mair
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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22
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Wang C, Bai X, Dong C, Guo Z, Yuan C. Friction properties of polyacrylamide hydrogel particle/HDPE composite under water lubrication. POLYMER 2019. [DOI: 10.1016/j.polymer.2019.121703] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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23
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Thoke HS, Bagatolli LA, Olsen LF. Effect of macromolecular crowding on the kinetics of glycolytic enzymes and the behaviour of glycolysis in yeast. Integr Biol (Camb) 2019; 10:587-597. [PMID: 30176029 DOI: 10.1039/c8ib00099a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Water is involved in all aspects of biological activity, both as a solvent and as a reactant. It is hypothesized that intracellular water is in a highly structured state due to the high concentrations of macromolecules in the cell and that this may change the activity of intracellular enzymes due to altered binding affinities and allosteric regulations. Here we first investigate the kinetics of two glycolytic enzymes in artificially crowded aqueous solutions and show that crowding does indeed change their kinetics. Based on our kinetic measurements we propose a new model of oscillating glycolysis that instead of Michaelis-Menten or Monod-Wyman-Changeux kinetics uses the Yang-Ling adsorption isotherm introduced by G. Ling in the frame of the Association-Induction (AI) hypothesis. Using this model, we can reproduce previous experimental observations of the coupling of glycolytic oscillations and intracellular water dynamics, e.g., (i) during the metabolic oscillations, the latter variable oscillates in phase with ATP activity, and (ii) the emergence of glycolytic oscillations largely depends on the extent of intracellular water dipolar relaxation in cells in the resting state. Our results support the view that the extent of intracellular water dipolar relaxation is regulated by the ability of cytoplasmic proteins to polarize intracellular water with the assistance of ATP, as suggested in the AI hypothesis. This hypothesis may be relevant to the interpretation of many other biological oscillators, including cell signalling processes.
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Affiliation(s)
- Henrik S Thoke
- Institute for Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK5230 Odense M, Denmark.
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24
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Abstract
Phagocytes protect the organism by ingesting harmful foreign particles and cells. We use mesoscale computer simulations to design a phagocyte-inspired active microcapsule that is capable of selectively capturing nanoparticles dispersed in solvent. Our fully synthetic microdevice is actuated by a temperature-sensitive microgel enclosed inside a perforated spherical shell. The shell pores are decorated with a copolymer brush that regulates the transport of solutes into the capsule interior. When exposed to an external stimulus, the microgel swells, expanding through the shell pores to make contact with the nanoparticle-rich solution surrounding the capsule. Upon removal of the external stimulus, the gel retracts back into the shell, bringing along with it captured nanoparticles. We probe how periodic application of the stimulus combined with nanoparticle-microgel adhesion enable selectivity and enhance capturing efficiency of our nature-inspired microdevice.
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Affiliation(s)
| | - Alberto Fernandez-Nieves
- Department of Condensed Matter Physics, University of Barcelona, 08028 Barcelona, Spain
- ICREA-Institucio Catalana de Recerca i Estudis Avancats, 08010 Barcelona, Spain
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25
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Orlov SN, Shiyan A, Boudreault F, Ponomarchuk O, Grygorczyk R. Search for Upstream Cell Volume Sensors: The Role of Plasma Membrane and Cytoplasmic Hydrogel. CURRENT TOPICS IN MEMBRANES 2018; 81:53-82. [PMID: 30243440 DOI: 10.1016/bs.ctm.2018.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
The plasma membrane plays a prominent role in the regulation of cell volume by mediating selective transport of extra- and intracellular osmolytes. Recent studies show that upstream sensors of cell volume changes are mainly located within the cytoplasm that displays properties of a hydrogel and not in the plasma membrane. Cell volume changes occurring in anisosmotic medium as well as in isosmotic environment affect properties of cytoplasmic hydrogel that, in turn, trigger rapid regulatory volume increase and decrease (RVI and RVD). The downstream signaling pathways include reorganization of 2D cytoskeleton and altered composition of polyphosphoinositides located on the inner surface of the plasma membrane. In addition to its action on physico-chemical properties of cytoplasmic hydrogel, cell volume changes in anisosmotic conditions affect the ionic strength of the cytoplasm and the [Na+]i/[K+]i ratio. Elevated intracellular ionic strength evoked by long term exposure of cells to hypertonic environment resulted in the activation of TonEBP and augmented expression of genes controlling intracellular organic osmolyte levels. The role of Na+i/K+i -sensitive, Ca2+i -mediated and Ca2+i-independent mechanisms of excitation-transcription coupling in cell volume-adjustment remains unknown.
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Affiliation(s)
- Sergei N Orlov
- Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia; Siberian State Medical University, Tomsk, Russia; National Research Tomsk State University, Tomsk, Russia
| | - Aleksandra Shiyan
- Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Francis Boudreault
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, Canada
| | - Olga Ponomarchuk
- Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia; Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, Canada
| | - Ryszard Grygorczyk
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, Canada; Department of Medicine, Faculty of Medicine, University of Montreal, Montreal, QC, Canada
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26
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Is a constant low-entropy process at the root of glycolytic oscillations? J Biol Phys 2018; 44:419-431. [PMID: 29796745 DOI: 10.1007/s10867-018-9499-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/01/2018] [Indexed: 01/04/2023] Open
Abstract
We measured temporal oscillations in thermodynamic variables such as temperature, heat flux, and cellular volume in suspensions of non-dividing yeast cells which exhibit temporal glycolytic oscillations. Oscillations in these variables have the same frequency as oscillations in the activity of intracellular metabolites, suggesting strong coupling between them. These results can be interpreted in light of a recently proposed theoretical formalism in which isentropic thermodynamic systems can display coupled oscillations in all extensive and intensive variables, reminiscent of adiabatic waves. This interpretation suggests that oscillations may be a consequence of the requirement of living cells for a constant low-entropy state while simultaneously performing biochemical transformations, i.e., remaining metabolically active. This hypothesis, which is in line with the view of the cellular interior as a highly structured and near equilibrium system where energy inputs can be low and sustain regular oscillatory regimes, calls into question the notion that metabolic processes are essentially dissipative.
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27
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Ponomarchuk OO, Boudreault F, Shiyan AA, Maksimov GV, Grygorczyk R, Orlov SN. A Method to Simultaneously Detect Changes in Intracellular Ca2+ Concentration and Cell Volume. Biophysics (Nagoya-shi) 2018. [DOI: 10.1134/s000635091803020x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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28
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Karabiyik Acar O, Kayitmazer AB, Torun Kose G. Hyaluronic Acid/Chitosan Coacervate-Based Scaffolds. Biomacromolecules 2018; 19:1198-1211. [DOI: 10.1021/acs.biomac.8b00047] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Ozge Karabiyik Acar
- Department of Genetics and Bioengineering, Yeditepe University, 34755, Istanbul, Turkey
| | | | - Gamze Torun Kose
- Department of Genetics and Bioengineering, Yeditepe University, 34755, Istanbul, Turkey
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29
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Thoke HS, Thorsteinsson S, Stock RP, Bagatolli LA, Olsen LF. The dynamics of intracellular water constrains glycolytic oscillations in Saccharomyces cerevisiae. Sci Rep 2017; 7:16250. [PMID: 29176686 PMCID: PMC5701229 DOI: 10.1038/s41598-017-16442-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 11/13/2017] [Indexed: 12/28/2022] Open
Abstract
We explored the dynamic coupling of intracellular water with metabolism in yeast cells. Using the polarity-sensitive probe 6-acetyl-2-dimethylaminonaphthalene (ACDAN), we show that glycolytic oscillations in the yeast S. cerevisiae BY4743 wild-type strain are coupled to the generalized polarization (GP) function of ACDAN, which measures the physical state of intracellular water. We analysed the oscillatory dynamics in wild type and 24 mutant strains with mutations in many different enzymes and proteins. Using fluorescence spectroscopy, we measured the amplitude and frequency of the metabolic oscillations and ACDAN GP in the resting state of all 25 strains. The results showed that there is a lower and an upper threshold of ACDAN GP, beyond which oscillations do not occur. This critical GP range is also phenomenologically linked to the occurrence of oscillations when cells are grown at different temperatures. Furthermore, the link between glycolytic oscillations and the ACDAN GP value also holds when ATP synthesis or the integrity of the cell cytoskeleton is perturbed. Our results represent the first demonstration that the dynamic behaviour of a metabolic process can be regulated by a cell-wide physical property: the dynamic state of intracellular water, which represents an emergent property.
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Affiliation(s)
- Henrik S Thoke
- Center for Biomembrane Physics (MEMPHYS), Odense M, Denmark.,Institute for Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK5230, Odense M, Denmark
| | - Sigmundur Thorsteinsson
- Institute for Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK5230, Odense M, Denmark
| | - Roberto P Stock
- Institute for Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK5230, Odense M, Denmark
| | - Luis A Bagatolli
- Center for Biomembrane Physics (MEMPHYS), Odense M, Denmark.,Yachay EP and Yachay Tech, Yachay City of Knowledge, 100650, Urcuquí-Imbabura, Ecuador
| | - Lars F Olsen
- Center for Biomembrane Physics (MEMPHYS), Odense M, Denmark. .,Institute for Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK5230, Odense M, Denmark.
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30
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Abstract
The emerging technological revolution in genetically encoded molecular sensors and super-resolution imaging provides neuroscientists with a pass to the real-time nano-world. On this small scale, however, classical principles of electrophysiology do not always apply. This is in large part because the nanoscopic heterogeneities in ionic concentrations and the local electric fields associated with individual ions and their movement can no longer be ignored. Here, we review basic principles of molecular electrodiffusion in the cellular environment of organized brain tissue. We argue that accurate interpretation of physiological observations on the nanoscale requires a better understanding of the underlying electrodiffusion phenomena.
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Abstract
Volume is an essential characteristic of a cell, and this review describes the main methods of its measurement that have been used in the past several decades. The discussed methods include various implementations of light scattering, estimates based on one or two cell dimensions, surface scanning, fluorescence confocal and transmission slice-by-slice imaging, intracellular volume markers, displacement of extracellular solution, quantitative phase imaging, radioactive methods, and some others. Suitability of these methods to some typical samples and applications is discussed. © 2017 International Society for Advancement of Cytometry.
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Affiliation(s)
- Michael A Model
- Department of Biological Sciences, Kent State University, Kent, Ohio
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32
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ElAfandy RT, AbuElela AF, Mishra P, Janjua B, Oubei HM, Büttner U, Majid MA, Ng TK, Merzaban JS, Ooi BS. Nanomembrane-Based, Thermal-Transport Biosensor for Living Cells. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2017; 13:1603080. [PMID: 27879037 DOI: 10.1002/smll.201603080] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 09/29/2016] [Indexed: 05/23/2023]
Abstract
Knowledge of materials' thermal-transport properties, conductivity and diffusivity, is crucial for several applications within areas of biology, material science and engineering. Specifically, a microsized, flexible, biologically integrated thermal transport sensor is beneficial to a plethora of applications, ranging across plants physiological ecology and thermal imaging and treatment of cancerous cells, to thermal dissipation in flexible semiconductors and thermoelectrics. Living cells pose extra challenges, due to their small volumes and irregular curvilinear shapes. Here a novel approach of simultaneously measuring thermal conductivity and diffusivity of different materials and its applicability to single cells is demonstrated. This technique is based on increasing phonon-boundary-scattering rate in nanomembranes, having extremely low flexural rigidities, to induce a considerable spectral dependence of the bandgap-emission over excitation-laser intensity. It is demonstrated that once in contact with organic or inorganic materials, the nanomembranes' emission spectrally shift based on the material's thermal diffusivity and conductivity. This NM-based technique is further applied to differentiate between different types and subtypes of cancer cells, based on their thermal-transport properties. It is anticipated that this novel technique to enable an efficient single-cell thermal targeting, allow better modeling of cellular thermal distribution and enable novel diagnostic techniques based on variations of single-cell thermal-transport properties.
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Affiliation(s)
- Rami T ElAfandy
- Photonics Laboratory, Computer, Electrical and Mathematical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Ayman F AbuElela
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Pawan Mishra
- Photonics Laboratory, Computer, Electrical and Mathematical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Bilal Janjua
- Photonics Laboratory, Computer, Electrical and Mathematical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Hassan M Oubei
- Photonics Laboratory, Computer, Electrical and Mathematical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Ulrich Büttner
- Microfluidics Core Lab, Computer, Electrical and Mathematical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Mohammed A Majid
- Photonics Laboratory, Computer, Electrical and Mathematical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Tien Khee Ng
- Photonics Laboratory, Computer, Electrical and Mathematical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Jasmeen S Merzaban
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Boon S Ooi
- Photonics Laboratory, Computer, Electrical and Mathematical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
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Vlaisavljevich E, Maxwell A, Mancia L, Johnsen E, Cain C, Xu Z. Visualizing the Histotripsy Process: Bubble Cloud-Cancer Cell Interactions in a Tissue-Mimicking Environment. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:2466-77. [PMID: 27401956 PMCID: PMC5010997 DOI: 10.1016/j.ultrasmedbio.2016.05.018] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 03/14/2016] [Accepted: 05/24/2016] [Indexed: 05/04/2023]
Abstract
Histotripsy is a non-invasive ultrasonic ablation method that uses cavitation to mechanically fractionate tissue into acellular debris. With a sufficient number of pulses, histotripsy can completely fractionate tissue into a liquid-appearing homogenate with no cellular structures. The location, shape and size of lesion formation closely match those of the cavitation cloud. Previous work has led to the hypothesis that the rapid expansion and collapse of histotripsy bubbles fractionate tissue by inducing large stress and strain on the tissue structures immediately adjacent to the bubbles. In the work described here, the histotripsy bulk tissue fractionation process is visualized at the cellular level for the first time using a custom-built 2-MHz transducer incorporated into a microscope stage. A layer of breast cancer cells were cultured within an optically transparent fibrin-based gel phantom to mimic cells inside a 3-D extracellular matrix. To test the hypothesis, the cellular response to single and multiple histotripsy pulses was investigated using high-speed optical imaging. Bubbles were always generated in the extracellular space, and significant cell displacement/deformation was observed for cells directly adjacent to the bubble during both bubble expansion and collapse. The largest displacements were observed during collapse for cells immediately adjacent to the bubble, with cells moving more than 150-300 μm in less than 100 μs. Cells often underwent multiple large deformations (>150% strain) over multiple pulses, resulting in the bisection of cells multiple times before complete removal. To provide theoretical support to the experimental observations, a numerical simulation was conducted using a single-bubble model, which indicated that histotripsy exerts the largest strains and cell displacements in the regions immediately adjacent to the bubble. The experimental and simulation results support our hypothesis, which helps to explain the formation of the sharp lesions formed in histotripsy therapy localized to the regions directly exposed to the bubbles.
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Affiliation(s)
- Eli Vlaisavljevich
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.
| | - Adam Maxwell
- Department of Urology, University of Washington, Seattle, Washington, USA
| | - Lauren Mancia
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Eric Johnsen
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Charles Cain
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Zhen Xu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA; Department of Pediatrics and Communicable Diseases, Division of Pediatric Cardiology, University of Michigan, Ann Arbor, Michigan, USA
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Joyner RP, Tang JH, Helenius J, Dultz E, Brune C, Holt LJ, Huet S, Müller DJ, Weis K. A glucose-starvation response regulates the diffusion of macromolecules. eLife 2016; 5. [PMID: 27003290 PMCID: PMC4811765 DOI: 10.7554/elife.09376] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 03/02/2016] [Indexed: 01/19/2023] Open
Abstract
The organization and biophysical properties of the cytosol implicitly govern molecular interactions within cells. However, little is known about mechanisms by which cells regulate cytosolic properties and intracellular diffusion rates. Here, we demonstrate that the intracellular environment of budding yeast undertakes a startling transition upon glucose starvation in which macromolecular mobility is dramatically restricted, reducing the movement of both chromatin in the nucleus and mRNPs in the cytoplasm. This confinement cannot be explained by an ATP decrease or the physiological drop in intracellular pH. Rather, our results suggest that the regulation of diffusional mobility is induced by a reduction in cell volume and subsequent increase in molecular crowding which severely alters the biophysical properties of the intracellular environment. A similar response can be observed in fission yeast and bacteria. This reveals a novel mechanism by which cells globally alter their properties to establish a unique homeostasis during starvation. DOI:http://dx.doi.org/10.7554/eLife.09376.001 Most organisms live in unpredictable environments, which can often lead to nutrient shortages and other conditions that limit their ability to grow. To survive in these harsh conditions, many organisms adopt a dormant state in which their metabolism slows down to conserve vital energy. When the environmental conditions improve, the organisms can return to their normal state and continue to grow. The interior of cells is known as the cytoplasm. It is very crowded and contains many molecules and compartments that carry out a variety of vital processes. The cytoplasm has long been considered to be fluid-like in nature, but recent evidence suggests that in bacterial cells it can solidify to resemble a glass-like material under certain conditions. When cells experience stress they stop dividing and alter their metabolism. However, it was not clear whether cells also alter their physical properties in response to changes in the environment. Now, Joyner et al. starve yeast cells of sugar and track the movements of two large molecules called mRNPs and chromatin. Chromatin is found in a cell compartment known as the nucleus, while mRNPs are found in the cytoplasm. The experiments show that during starvation, both molecules are less able to move around in their respective areas of the cell. This appears to be due to water loss from the cells, which causes the cells to become smaller and leads to the interior of the cell becoming more crowded. Joyner et al. also observed a similar response in bacteria. Furthermore, Joyner et al. suggest that the changes in physical properties are critical for cells to survive the stress caused by starvation. A separate study by Munder et al. found that when cells become dormant the cytoplasm becomes more acidic, which causes many proteins to bind to each other and form large clumps. Together, the findings of the studies suggest that the interior of cells can undergo a transition from a fluid-like to a more solid-like state to protect the cells from damage when energy is in short supply. The next challenge is to understand the molecular mechanisms that cause the physical properties of the cells to change under different conditions. DOI:http://dx.doi.org/10.7554/eLife.09376.002
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Affiliation(s)
- Ryan P Joyner
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Jeffrey H Tang
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zürich, Switzerland
| | - Jonne Helenius
- Department of Biosystems Science and Engineering, ETH Zurich, Zürich, Switzerland
| | - Elisa Dultz
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Christiane Brune
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Liam J Holt
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Sebastien Huet
- CNRS, UMR 6290, Institut Génétique et Développement, University of Rennes, Rennes, France
| | - Daniel J Müller
- Department of Biosystems Science and Engineering, ETH Zurich, Zürich, Switzerland
| | - Karsten Weis
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,Institute of Biochemistry, Department of Biology, ETH Zurich, Zürich, Switzerland
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Munder MC, Midtvedt D, Franzmann T, Nüske E, Otto O, Herbig M, Ulbricht E, Müller P, Taubenberger A, Maharana S, Malinovska L, Richter D, Guck J, Zaburdaev V, Alberti S. A pH-driven transition of the cytoplasm from a fluid- to a solid-like state promotes entry into dormancy. eLife 2016; 5. [PMID: 27003292 PMCID: PMC4850707 DOI: 10.7554/elife.09347] [Citation(s) in RCA: 277] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 02/13/2016] [Indexed: 01/19/2023] Open
Abstract
Cells can enter into a dormant state when faced with unfavorable conditions. However, how cells enter into and recover from this state is still poorly understood. Here, we study dormancy in different eukaryotic organisms and find it to be associated with a significant decrease in the mobility of organelles and foreign tracer particles. We show that this reduced mobility is caused by an influx of protons and a marked acidification of the cytoplasm, which leads to widespread macromolecular assembly of proteins and triggers a transition of the cytoplasm to a solid-like state with increased mechanical stability. We further demonstrate that this transition is required for cellular survival under conditions of starvation. Our findings have broad implications for understanding alternative physiological states, such as quiescence and dormancy, and create a new view of the cytoplasm as an adaptable fluid that can reversibly transition into a protective solid-like state.
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Affiliation(s)
| | - Daniel Midtvedt
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
| | - Titus Franzmann
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Elisabeth Nüske
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Oliver Otto
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Maik Herbig
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Elke Ulbricht
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Paul Müller
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Anna Taubenberger
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Shovamayee Maharana
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Liliana Malinovska
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Doris Richter
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Jochen Guck
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Vasily Zaburdaev
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
| | - Simon Alberti
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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Role of cytoskeleton network in anisosmotic volume changes of intact and permeabilized A549 cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:2337-43. [PMID: 26171817 DOI: 10.1016/j.bbamem.2015.07.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 07/06/2015] [Accepted: 07/10/2015] [Indexed: 11/20/2022]
Abstract
Recently we found that cytoplasm of permeabilized mammalian cells behaves as a hydrogel displaying intrinsic osmosensitivity. This study examined the role of microfilaments and microtubules in the regulation of hydrogel osmosensitivity, volume-sensitive ion transporters, and their contribution to volume modulation of intact cells. We found that intact and digitonin-permeabilized A549 cells displayed similar rate of shrinkage triggered by hyperosmotic medium. It was significantly slowed-down in both cell preparations after disruption of actin microfilaments by cytochalasin B, suggesting that rapid water release by intact cytoplasmic hydrogel contributes to hyperosmotic shrinkage. In hyposmotic swelling experiments, disruption of microtubules by vinblastine attenuated the maximal amplitude of swelling in intact cells and completely abolished it in permeabilized cells. The swelling of intact cells also triggered ~10-fold elevation of furosemide-resistant (86)Rb+ (K+) permeability and the regulatory volume decrease (RVD), both of which were abolished by Ba2+. Interestingly, RVD and K+ permeability remained unaffected in cytocholasin/vinblastine treated cells demonstrating that cytoskeleton disruption has no direct impact on Ba2+-sensitive K+-channels involved in RVD. Our results show, for the first time, that the cytoskeleton network contributes directly to passive cell volume adjustments in anisosmotic media via the modulation of the water retained by the cytoplasmic hydrogel.
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37
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Tanaka A, Nakashima H, Kashimura Y, Sumitomo K. Electrostatically induced planar lipid membrane formation on a cationic hydrogel array by the fusion of small negatively charged unilamellar vesicles. Colloids Surf A Physicochem Eng Asp 2015. [DOI: 10.1016/j.colsurfa.2015.03.049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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38
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Peters W, Kusche-Vihrog K, Oberleithner H, Schillers H. Cystic fibrosis transmembrane conductance regulator is involved in polyphenol-induced swelling of the endothelial glycocalyx. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2015; 11:1521-30. [PMID: 25881741 DOI: 10.1016/j.nano.2015.03.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 03/15/2015] [Accepted: 03/23/2015] [Indexed: 12/21/2022]
Abstract
UNLABELLED Previous studies show that polyphenol-rich compounds can induce a swelling of the endothelial glycocalyx (eGC). Our goal was to reveal the mechanism behind the eGC-swelling. As polyphenols are potent modulators of fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel, the hypothesis was tested whether polyphenol-induced increase in CFTR activity is responsible for the eGC-swelling. The impact of the polyphenols resveratrol, (-)-epicatechin, and quercetin on nanomechanics of living endothelial GM7373 cells was monitored by AFM-nanoindentation. The tested polyphenols lead to eGC-swelling with a simultaneous decrease in cortical stiffness. EGC-swelling, but not the change in cortical stiffness, was prevented by the inhibition of CFTR. Polyphenol-induced eGC-swelling could be mimicked by cytochalasin D, an actin-depolymerizing agent. Thus, in the vascular endothelium, polyphenols induce eGC-swelling by softening cortical actin and activating CFTR. Our findings imply that CFTR plays an important role in the maintenance of vascular homeostasis and may explain the vasoprotective properties of polyphenols. FROM THE CLINICAL EDITOR Many vascular problems clinically can be attributed to a dysregulation of endothelial glycocalyx (eGC). The underlying mechanism however remains unclear. In this article, the authors used nanoindentation and showed that polyphenols could swell the endothelial glycocalyx and alter its function. This investigative method can lead to further mechanistic studies of other molecular pathways.
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Affiliation(s)
- Wladimir Peters
- Institute of Physiology II, University of Münster, Münster, Germany
| | | | | | - Hermann Schillers
- Institute of Physiology II, University of Münster, Münster, Germany.
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39
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Thoke HS, Tobiesen A, Brewer J, Hansen PL, Stock RP, Olsen LF, Bagatolli LA. Tight coupling of metabolic oscillations and intracellular water dynamics in Saccharomyces cerevisiae. PLoS One 2015; 10:e0117308. [PMID: 25705902 PMCID: PMC4338026 DOI: 10.1371/journal.pone.0117308] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 12/22/2014] [Indexed: 01/20/2023] Open
Abstract
We detected very strong coupling between the oscillating concentration of ATP and the dynamics of intracellular water during glycolysis in Saccharomyces cerevisiae. Our results indicate that: i) dipolar relaxation of intracellular water is heterogeneous within the cell and different from dilute conditions, ii) water dipolar relaxation oscillates with glycolysis and in phase with ATP concentration, iii) this phenomenon is scale-invariant from the subcellular to the ensemble of synchronized cells and, iv) the periodicity of both glycolytic oscillations and dipolar relaxation are equally affected by D2O in a dose-dependent manner. These results offer a new insight into the coupling of an emergent intensive physicochemical property of the cell, i.e. cell-wide water dipolar relaxation, and a central metabolite (ATP) produced by a robustly oscillating metabolic process.
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Affiliation(s)
- Henrik Seir Thoke
- MEMPHYS—Center for Biomembrane Physics, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK5230, Odense M, Denmark
| | - Asger Tobiesen
- MEMPHYS—Center for Biomembrane Physics, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK5230, Odense M, Denmark
| | - Jonathan Brewer
- MEMPHYS—Center for Biomembrane Physics, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK5230, Odense M, Denmark
| | - Per Lyngs Hansen
- MEMPHYS—Center for Biomembrane Physics, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK5230, Odense M, Denmark
| | - Roberto P. Stock
- Instituto de Biotecnología, Universidad Nacional Autónoma de México (IBt-UNAM), Av. Universidad 2001, Cuernavaca, Morelos, 62210, Mexico
| | - Lars F. Olsen
- CelCom group, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK5230, Odense M, Denmark
| | - Luis A. Bagatolli
- MEMPHYS—Center for Biomembrane Physics, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK5230, Odense M, Denmark
- * E-mail:
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40
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Salt and osmosensing: role of cytoplasmic hydrogel. Pflugers Arch 2015; 467:475-87. [DOI: 10.1007/s00424-014-1680-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 12/17/2014] [Accepted: 12/18/2014] [Indexed: 12/30/2022]
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41
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Orlov SN, Model MA, Grygorczyk R. CrossTalk opposing view: The triggering and progression of the cell death machinery can occur without cell volume perturbations. J Physiol 2014; 591:6123-5. [PMID: 24339146 DOI: 10.1113/jphysiol.2013.258624] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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42
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Temperature-Induced Inactivation of Cytoplasmic Biogel Osmosensing Properties is Associated with Suppression of Regulatory Volume Decrease in A549 Cells. J Membr Biol 2014; 247:571-9. [DOI: 10.1007/s00232-014-9673-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 05/06/2014] [Indexed: 10/25/2022]
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43
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Cameron IL, Fullerton GD. Lack of appreciation of the role of osmotically unresponsive water in cell volume regulation. Cell Biol Int 2014; 38:610-4. [PMID: 24375657 DOI: 10.1002/cbin.10238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 12/23/2013] [Indexed: 11/11/2022]
Abstract
The osmotic responsiveness of cell water has been re-evaluated of reports on the osmotic behaviour of cells. In seven animal cell types, the osmotically unresponsive water (OUR) fraction values ranged from 0.75 to 2.41 g water/g dry mass (g/g), and from 25 to 92% of the total cell water. Protein confirmation, aggregation and crowding play a major, but under-recognised, role in determining the extent of OUR and the regulation of cell volume. Volume regulation studies that do not take into account the role of OUR must be judged incomplete.
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Affiliation(s)
- Ivan L Cameron
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229-3900, USA
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44
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Live fluorescence and transmission-through-dye microscopic study of actinomycin D-induced apoptosis and apoptotic volume decrease. Apoptosis 2014; 18:521-32. [PMID: 23325449 DOI: 10.1007/s10495-013-0804-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The effect of actinomycin D on HeLa cells was studied by live fluorescence and transmission-through-dye microscopy-a recently developed technique that permits volume measurements in live cells. In particular, it is well suited for the observation and quantification of the apoptotic volume decrease (AVD), which is widely viewed as an essential feature of apoptosis. The main results from our study are as follows. (1) Apoptosis caused in HeLa cells by actinomycin D proceeds in two morphologically distinct stages: the early stage is characterized by extensive blebbing, and the late stage by a more compact shape. The loss of mitochondrial membrane potential occurs at about the same time as blebbing, and chromatin condensation follows 30-90 min later. Caspase-3 and 7 become activated during the late stage. (2) Because blebbing occurs before activation of caspase-3, it has to be initiated by a different mechanism. Although blebbing is one of the earliest observable changes, it can be selectively inhibited without affecting other apoptotic reactions. (3) The majority of cells experience a temporary volume increase after the appearance of blebs. Eventually, AVD takes over and the cells shrink by approximately 40 % of their initial volume; the volume loss becomes noticeable at the end of the blebbing phase and continues through the late stage. Sometimes, at the end of long incubations, shrinkage gives way to swelling, possibly indicating secondary necrosis. (4) Both early and late apoptosis are accompanied by intracellular accumulation of Na(+), while low-sodium medium prevents apoptosis. Except for a partial protective effect of quinine, all of the tested blockers of Na(+), K(+) and Cl(-) channels failed to prevent apoptosis or AVD.
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45
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Enhanced transcription and translation in clay hydrogel and implications for early life evolution. Sci Rep 2013; 3:3165. [PMID: 24196527 PMCID: PMC3819617 DOI: 10.1038/srep03165] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 10/11/2013] [Indexed: 11/08/2022] Open
Abstract
In most contemporary life forms, the confinement of cell membranes provides localized concentration and protection for biomolecules, leading to efficient biochemical reactions. Similarly, confinement may have also played an important role for prebiotic compartmentalization in early life evolution when the cell membrane had not yet formed. It remains an open question how biochemical reactions developed without the confinement of cell membranes. Here we mimic the confinement function of cells by creating a hydrogel made from geological clay minerals, which provides an efficient confinement environment for biomolecules. We also show that nucleic acids were concentrated in the clay hydrogel and were protected against nuclease, and that transcription and translation reactions were consistently enhanced. Taken together, our results support the importance of localized concentration and protection of biomolecules in early life evolution, and also implicate a clay hydrogel environment for biochemical reactions during early life evolution.
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46
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Sing CE, Zwanikken JW, Olvera de la Cruz M. Effect of Ion–Ion Correlations on Polyelectrolyte Gel Collapse and Reentrant Swelling. Macromolecules 2013. [DOI: 10.1021/ma400372p] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Charles E. Sing
- Department of Materials
Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Jos W. Zwanikken
- Department of Materials
Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Monica Olvera de la Cruz
- Department of Materials
Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
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47
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Orlov SN, Platonova AA, Hamet P, Grygorczyk R. Cell volume and monovalent ion transporters: their role in cell death machinery triggering and progression. Am J Physiol Cell Physiol 2013; 305:C361-72. [PMID: 23615964 DOI: 10.1152/ajpcell.00040.2013] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cell death is accompanied by the dissipation of electrochemical gradients of monovalent ions across the plasma membrane that, in turn, affects cell volume via modulation of intracellular osmolyte content. In numerous cell types, apoptotic and necrotic stimuli caused cell shrinkage and swelling, respectively. Thermodynamics predicts a cell type-specific rather than an ubiquitous impact of monovalent ion transporters on volume perturbations in dying cells, suggesting their diverse roles in the cell death machinery. Indeed, recent data showed that apoptotic collapse may occur in the absence of cell volume changes and even follow cell swelling rather than shrinkage. Moreover, side-by-side with cell volume adjustment, monovalent ion transporters contribute to cell death machinery engagement independently of volume regulation via cell type-specific signaling pathways. Thus, inhibition of Na(+)-K(+)-ATPase by cardiotonic steroids (CTS) rescues rat vascular smooth muscle cells from apoptosis via a novel Na(+)i-K(+)i-mediated, Ca(2+)i-independent mechanism of excitation-transcription coupling. In contrast, CTS kill renal epithelial cells independently of Na(+)-K(+)-ATPase inhibition and increased [Na(+)]i/[K(+)]i ratio. The molecular origin of [Na(+)]i/[K(+)]i sensors involved in the inhibition of apoptosis as well as upstream intermediates of Na(+)i/K(+)i-independent death signaling triggered by CTS remain unknown.
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Affiliation(s)
- Sergei N Orlov
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada.
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48
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Koltsova SV, Akimova OA, Kotelevtsev SV, Grygorczyk R, Orlov SN. Hyperosmotic and isosmotic shrinkage differentially affect protein phosphorylation and ion transport. Can J Physiol Pharmacol 2012; 90:209-17. [DOI: 10.1139/y11-119] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the present work, we compared the outcome of hyperosmotic and isosmotic shrinkage on ion transport and protein phosphorylation in C11-MDCK cells resembling intercalated cells from collecting ducts and in vascular smooth muscle cells (VSMC) from the rat aorta. Hyperosmotic shrinkage was triggered by cell exposure to hypertonic medium, whereas isosmotic shrinkage was evoked by cell transfer from an hypoosmotic to an isosmotic environment. Despite a similar cell volume decrease of 40%–50%, the consequences of hyperosmotic and isosmotic shrinkage on cellular functions were sharply different. In C11-MDCK and VSMC, hyperosmotic shrinkage completely inhibited Na+,K+-ATPase and Na+,Pi cotransport. In contrast, in both types of cells isosmotic shrinkage slightly increased rather than suppressed Na+,K+-ATPase and did not change Na+,Pi cotransport. In C11-MDCK cells, phosphorylation of JNK1/2 and Erk1/2 mitogen-activated protein kinases was augmented in hyperosmotically shrunken cells by ∼7- and 2-fold, respectively, but was not affected in cells subjected to isosmotic shrinkage. These results demonstrate that the data obtained in cells subjected to hyperosmotic shrinkage cannot be considered as sufficient proof implicating cell volume perturbations in the regulation of cellular functions under isosmotic conditions.
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Affiliation(s)
- Svetlana V. Koltsova
- Research Centre, Centre hospitalier de l’Université de Montréal (CHUM) – Technopôle Angus, Montreal, QC H1W 4A4, Canada
| | - Olga A. Akimova
- Research Centre, Centre hospitalier de l’Université de Montréal (CHUM) – Technopôle Angus, Montreal, QC H1W 4A4, Canada
| | | | - Ryszard Grygorczyk
- Research Centre, Centre hospitalier de l’Université de Montréal (CHUM) – Technopôle Angus, Montreal, QC H1W 4A4, Canada
| | - Sergei N. Orlov
- Research Centre, Centre hospitalier de l’Université de Montréal (CHUM) – Technopôle Angus, Montreal, QC H1W 4A4, Canada
- Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
- Institute of General Pathology and Pathophysiology of the Russian Academy of Medical Sciences, Moscow, Russia
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YUSIPOVICH AI, ZAGUBIZHENKO MV, LEVIN GG, PLATONOVA A, PARSHINA EY, GRYGORZCYK R, MAKSIMOV GV, RUBIN AB, ORLOV SN. Laser interference microscopy of amphibian erythrocytes: impact of cell volume and refractive index. J Microsc 2011; 244:223-9. [DOI: 10.1111/j.1365-2818.2011.03516.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Platonova A, Koltsova S, Maksimov GV, Grygorczyk R, Orlov SN. The death of ouabain-treated renal epithelial C11-MDCK cells is not mediated by swelling-induced plasma membrane rupture. J Membr Biol 2011; 241:145-54. [PMID: 21584679 DOI: 10.1007/s00232-011-9371-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 05/05/2011] [Indexed: 10/18/2022]
Abstract
This study examined the role of cell volume modulation in plasma membrane rupture and death documented in ouabain-treated renal epithelial cells. Long-term exposure to ouabain caused massive death of C11-MDCK (Madin-Darby canine kidney) epithelial cells, documented by their detachment, chromatin cleavage and complete loss of lactate dehydrogenase (LDH), but did not affect the survival of vascular smooth muscle cells (VSMCs) from the rat aorta. Unlike the distinct impact on cell survival, 2-h exposure to ouabain led to sharp elevation of the [Na⁺](i)/[K⁺](i) ratio in both cell types. A similar increment of Na⁺(i) content was evoked by sustained inhibition of Na⁺,K⁺-ATPase in K⁺-free medium. However, in contrast to ouabain, C11-MDCK cells survived perfectly during 24-h exposure to K⁺-free medium. At 3 h, the volume of ouabain-treated C11-MDCK cells and VSMCs, measured by the recently developed dual-image surface reconstruction technique, was increased by 16 and 12%, respectively, whereas 5-10 min before the detachment of ouabain-treated C11-MDCK cells, their volume was augmented by ~30-40%. To examine the role of modest swelling in the plasma membrane rupture of ouabain-treated cells, we compared actions of hypotonic medium on volume and LDH release. We observed that LDH release from hypoosmotically swollen C11-MDCK cells was triggered when their volume was increased by approximately fivefold. Thus, our results showed that the rupture of plasma membranes in ouabain-treated C11-MDCK cells was not directly caused by cell volume modulation evoked by Na⁺,K⁺-ATPase inhibition and inversion of the [Na⁺](i)/[K⁺](i) ratio.
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Affiliation(s)
- Alexandra Platonova
- Research Centre, Centre Hospitalier de l'Université de Montréal (CRCHUM)-Technopôle Angus, 2901 Rachel Est, Montreal, QC H1W4A4, Canada
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