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Liu X, Wei Y, Li W, Li B, Liu L. Cytoskeleton induced the changes of microvilli and mechanical properties in living cells by atomic force microscopy. J Cell Physiol 2020; 236:3725-3733. [PMID: 33169846 DOI: 10.1002/jcp.30110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/08/2020] [Accepted: 10/05/2020] [Indexed: 01/05/2023]
Abstract
The cytoskeleton acts as a scaffold for membrane protrusion, such as microvilli. However, the relationship between the characteristics of microvilli and cytoskeleton remains poorly understood under the physiological state. To investigate the role of the cytoskeleton in regulating microvilli and cellular mechanical properties, atomic force microscopy (AFM) was used to detect the dynamic characteristics of microvillus morphology and elastic modulus of living HeLa cells. First, HeLa and MCF-7 cell lines were stained with Fluor-488-phalloidin and microtubules antibody. Then, the microvilli morphology was analyzed by high-resolution images of AFM in situ. Furthermore, changes in elastic modulus were investigated by the force curve of AFM. Fluorescence microscopy and AFM results revealed that destroyed microfilaments led to a smaller microvilli size, whereas the increase in the aggregation and number of microfilaments led to a larger microvilli size. The destruction and aggregation of microfilaments remarkably affected the mechanical properties of HeLa cells. Microtubule-related drugs induced the change of microtubule, but we failed to note significant differences in microvilli morphology and mechanical properties of cells. In summary, our results unraveled the relationship between microfilaments and the structure of microvilli and Young's modulus in living HeLa cells, which would contribute to the further understanding of the physiological function of the cytoskeleton in vivo.
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Affiliation(s)
- Xueyan Liu
- Key Laboratory of Medicine, School of Laboratory Medicine and Life Sciences, Ministry of Education of China, Wenzhou Medical University, Wenzhou, China
| | - Yuhui Wei
- Division of Physical Biology and Bioimaging Centre, Shanghai Synchrotron Radiation Facility, CAS Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai, China.,Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Wei Li
- Key Laboratory of Medicine, School of Laboratory Medicine and Life Sciences, Ministry of Education of China, Wenzhou Medical University, Wenzhou, China.,Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, China
| | - Bin Li
- Division of Physical Biology and Bioimaging Centre, Shanghai Synchrotron Radiation Facility, CAS Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai, China.,Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Lin Liu
- Key Laboratory of Medicine, School of Laboratory Medicine and Life Sciences, Ministry of Education of China, Wenzhou Medical University, Wenzhou, China.,Division of Physical Biology and Bioimaging Centre, Shanghai Synchrotron Radiation Facility, CAS Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai, China.,Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, China
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2
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Chtcheglova LA, Ohlmann A, Boytsov D, Hinterdorfer P, Priglinger SG, Priglinger CS. Nanoscopic Approach to Study the Early Stages of Epithelial to Mesenchymal Transition (EMT) of Human Retinal Pigment Epithelial (RPE) Cells In Vitro. Life (Basel) 2020; 10:E128. [PMID: 32751632 PMCID: PMC7460373 DOI: 10.3390/life10080128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/21/2020] [Accepted: 07/28/2020] [Indexed: 12/23/2022] Open
Abstract
The maintenance of visual function is supported by the proper functioning of the retinal pigment epithelium (RPE), representing a mosaic of polarized cuboidal postmitotic cells. Damage factors such as inflammation, aging, or injury can initiate the migration and proliferation of RPE cells, whereas they undergo a pseudo-metastatic transformation or an epithelial to mesenchymal transition (EMT) from cuboidal epithelioid into fibroblast-like or macrophage-like cells. This process is recognized as a key feature in several severe ocular pathologies, and is mimicked by placing RPE cells in culture, which provides a reasonable and well-characterized in vitro model for a type 2 EMT. The most obvious characteristic of EMT is the cell phenotype switching, accompanied by the cytoskeletal reorganization with changes in size, shape, and geometry. Atomic force microscopy (AFM) has the salient ability to label-free explore these characteristics. Based on our AFM results supported by the genetic analysis of specific RPE differentiation markers, we elucidate a scheme for gradual transformation from the cobblestone to fibroblast-like phenotype. Structural changes in the actin cytoskeletal reorganization at the early stages of EMT lead to the development of characteristic geodomes, a finding that may reflect an increased propensity of RPE cells to undergo further EMT and thus become of diagnostic significance.
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Affiliation(s)
- Lilia A. Chtcheglova
- Institute of Biophysics, Johannes Kepler University (JKU) Linz, Gruberstrasse 40, 4020 Linz, Austria; (D.B.); (P.H.)
| | - Andreas Ohlmann
- Department of Ophthalmology, Munich University Hospital, Ludwig-Maximilians-University (LMU) Munich, Mathildenstrasse 8, 80336 Munich, Germany; (A.O.); (S.G.P.); (C.S.P.)
| | - Danila Boytsov
- Institute of Biophysics, Johannes Kepler University (JKU) Linz, Gruberstrasse 40, 4020 Linz, Austria; (D.B.); (P.H.)
| | - Peter Hinterdorfer
- Institute of Biophysics, Johannes Kepler University (JKU) Linz, Gruberstrasse 40, 4020 Linz, Austria; (D.B.); (P.H.)
| | - Siegfried G. Priglinger
- Department of Ophthalmology, Munich University Hospital, Ludwig-Maximilians-University (LMU) Munich, Mathildenstrasse 8, 80336 Munich, Germany; (A.O.); (S.G.P.); (C.S.P.)
| | - Claudia S. Priglinger
- Department of Ophthalmology, Munich University Hospital, Ludwig-Maximilians-University (LMU) Munich, Mathildenstrasse 8, 80336 Munich, Germany; (A.O.); (S.G.P.); (C.S.P.)
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3
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Starvation effect on the morphology of microvilli in HeLa cells. Biochem Biophys Res Commun 2019; 514:1238-1243. [DOI: 10.1016/j.bbrc.2019.05.073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 05/09/2019] [Indexed: 01/03/2023]
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4
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Zhang X, Ren J, Wang J, Li S, Zou Q, Gao N. Receptor-mediated endocytosis generates nanomechanical force reflective of ligand identity and cellular property. J Cell Physiol 2018; 233:5908-5919. [PMID: 29243828 DOI: 10.1002/jcp.26400] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 12/12/2017] [Indexed: 01/07/2023]
Abstract
Whether environmental (thermal, chemical, and nutrient) signals generate quantifiable, nanoscale, mechanophysical changes in the cellular plasma membrane has not been well elucidated. Assessment of such mechanophysical properties of plasma membrane may shed lights on fundamental cellular process. Atomic force microscopic (AFM) measurement of the mechanical properties of live cells was hampered by the difficulty in accounting for the effects of the cantilever motion and the associated hydrodynamic force on the mechanical measurement. These challenges have been addressed in our recently developed control-based AFM nanomechanical measurement protocol, which enables a fast, noninvasive, broadband measurement of the real-time changes in plasma membrane elasticity in live cells. Here we show using this newly developed AFM platform that the plasma membrane of live mammalian cells exhibits a constant and quantifiable nanomechanical property, the membrane elasticity. This mechanical property sensitively changes in response to environmental factors, such as the thermal, chemical, and growth factor stimuli. We demonstrate that different chemical inhibitors of endocytosis elicit distinct changes in plasma membrane elastic modulus reflecting their specific molecular actions on the lipid configuration or the endocytic machinery. Interestingly, two different growth factors, EGF and Wnt3a, elicited distinct elastic force profiles revealed by AFM at the plasma membrane during receptor-mediated endocytosis. By applying this platform to genetically modified cells, we uncovered a previously unknown contribution of Cdc42, a key component of the cellular trafficking network, to EGF-stimulated endocytosis at plasma membrane. Together, this nanomechanical AFM study establishes an important foundation that is expandable and adaptable for investigation of cellular membrane evolution in response to various key extracellular signals.
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Affiliation(s)
- Xiao Zhang
- Department of Biological Sciences, Rutgers University, Newark, New Jersey
| | - Juan Ren
- Department of Mechanical Engineering, Iowa State University, Ames, Iowa
| | - Jingren Wang
- Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, New Jersey
| | - Shixie Li
- Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, New Jersey
| | - Qingze Zou
- Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, New Jersey
| | - Nan Gao
- Department of Biological Sciences, Rutgers University, Newark, New Jersey
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5
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Franz J, Grünebaum J, Schäfer M, Mulac D, Rehfeldt F, Langer K, Kramer A, Riethmüller C. Rhombic organization of microvilli domains found in a cell model of the human intestine. PLoS One 2018; 13:e0189970. [PMID: 29320535 PMCID: PMC5761853 DOI: 10.1371/journal.pone.0189970] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 12/05/2017] [Indexed: 01/22/2023] Open
Abstract
Symmetry is rarely found on cellular surfaces. An exception is the brush border of microvilli, which are essential for the proper function of transport epithelia. In a healthy intestine, they appear densely packed as a 2D-hexagonal lattice. For in vitro testing of intestinal transport the cell line Caco-2 has been established. As reported by electron microscopy, their microvilli arrange primarily in clusters developing secondly into a 2D-hexagonal lattice. Here, atomic force microscopy (AFM) was employed under aqueous buffer conditions on Caco-2 cells, which were cultivated on permeable filter membranes for optimum differentiation. For analysis, the exact position of each microvillus was detected by computer vision; subsequent Fourier transformation yielded the type of 2D-lattice. It was confirmed, that Caco-2 cells can build a hexagonal lattice of microvilli and form clusters. Moreover, a second type of arrangement was discovered, namely a rhombic lattice, which appeared at sub-maximal densities of microvilli with (29 ± 4) microvilli / μm2. Altogether, the findings indicate the existence of a yet undescribed pattern in cellular organization.
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Affiliation(s)
- Jonas Franz
- Faculty of Physics, Georg-August-Universität, Göttingen, Germany
- Max Planck Institute for Dynamics and Self-Organization, Theoretical Neurophysics, Göttingen, Germany
| | - Jonas Grünebaum
- Institute for Pharmaceutical Technology and Biopharmacy, University of Münster, Münster, Germany
| | - Marcus Schäfer
- nanoAnalytics GmbH, Centre for Nanotechnology, Münster, Germany
| | - Dennis Mulac
- Institute for Pharmaceutical Technology and Biopharmacy, University of Münster, Münster, Germany
| | - Florian Rehfeldt
- Third Institute of Physics—Biophysics, Georg-August-Universität, Göttingen, Germany
| | - Klaus Langer
- Institute for Pharmaceutical Technology and Biopharmacy, University of Münster, Münster, Germany
| | - Armin Kramer
- Serend-ip GmbH, Centre for Nanotechnology, Münster, Germany
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Tu LY, Bai HH, Cai JY, Deng SP. The mechanism of kaempferol induced apoptosis and inhibited proliferation in human cervical cancer SiHa cell: From macro to nano. SCANNING 2016; 38:644-653. [PMID: 26890985 DOI: 10.1002/sca.21312] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 02/05/2016] [Indexed: 05/10/2023]
Abstract
Kaempferol has been identified as a potential cancer therapeutic agent by an increasing amount of evidences. However, the changes in the topography of cell membrane induced by kaempferol at subcellular- or nanometer-level were still unclear. In this work, the topographical changes of cytomembrane in human cervical cancer cell (SiHa) induced by kaempferol, as well as the role of kaempferol in apoptosis induction and its possible mechanisms, were investigated. At the macro level, MTT assays showed that kaempferol inhibited the proliferation of SiHa cells in a time- and dose-dependent manner. Flow cytometry analysis demonstrated that kaempferol could induce SiHa cell apoptosis, mitochondrial membrane potential disruption, and intracellular free calcium elevation. At the micro level, fluorescence imaging by laser scanning confocal microscopy (LSCM) indicated that kaempferol could also destroy the networks of microtubules. Using high resolution atomic force microscopy (AFM), we determined the precise changes of cellular membrane induced by kaempferol at subcellular or nanometer level. The spindle-shaped SiHa cells shrank after kaempferol treatment, with significantly increased cell surface roughness. These data showed structural characterizations of cellular topography in kaempferol-induced SiHa cell apoptosis and might provide novel integrated information from macro to nano level to assess the impact of kaempferol on cancer cells, which might be important for the understanding of the anti-cancer mechanisms of drugs. SCANNING 38:644-653, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Lv-Ying Tu
- Department of Chemistry, Jinan University, Guangzhou, P. R. China
| | - Hai-Hua Bai
- Department of Chemistry, Jinan University, Guangzhou, P. R. China
| | - Ji-Ye Cai
- Department of Chemistry, Jinan University, Guangzhou, P. R. China
- State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Macau, P. R. China
| | - Sui-Ping Deng
- Department of Chemistry, Jinan University, Guangzhou, P. R. China
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López-Ortega O, Ovalle-García E, Ortega-Blake I, Antillón A, Chávez-Munguía B, Patiño-López G, Fragoso-Soriano R, Santos-Argumedo L. Myo1g is an active player in maintaining cell stiffness in B-lymphocytes. Cytoskeleton (Hoboken) 2016; 73:258-68. [DOI: 10.1002/cm.21299] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 04/11/2016] [Accepted: 04/13/2016] [Indexed: 12/11/2022]
Affiliation(s)
- O. López-Ortega
- Departamento De Biomedicina Molecular; Centro De Investigación Y De Estudios Avanzados Del Instituto Politécnico Nacional; Ciudad De México C. P. 07360 México
- Facultad De Medicina, Universidad Nacional Autónoma De México; Ciudad De México C. P. 04510 México
| | - E. Ovalle-García
- Universidad Autónoma De Nuevo León, UANL. Facultad De Ingeniería Mecánica Y Eléctrica, Av. Universidad S/N, Ciudad Universitaria, San Nicolás De Los Garza; Nuevo León C. P. 66451 México
| | - I. Ortega-Blake
- Instituto De Ciencias Físicas, UNAM; Cuernavaca Morelos C. P. 62210 México
| | - A. Antillón
- Instituto De Ciencias Físicas, UNAM; Cuernavaca Morelos C. P. 62210 México
| | - B. Chávez-Munguía
- Departamento De Infectómica Y Patogénesis Molecular; Centro De Investigación Y De Estudios Avanzados Del Instituto Politécnico Nacional; Ciudad De México C. P. 07360 México
| | - G. Patiño-López
- Laboratorio De Investigación En Inmunología Y Proteómica, Hospital Infantil De México, “Federico Gómez”; Ciudad De México C. P. 06720 México
| | - R. Fragoso-Soriano
- Departamento De Física; Centro De Investigación Y De Estudios Avanzados Del Instituto Politécnico Nacional; Ciudad De México C. P. 07360 México
| | - L. Santos-Argumedo
- Departamento De Biomedicina Molecular; Centro De Investigación Y De Estudios Avanzados Del Instituto Politécnico Nacional; Ciudad De México C. P. 07360 México
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8
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Tu LY, Pi J, Jin H, Cai JY, Deng SP. Synthesis, characterization and anticancer activity of kaempferol-zinc(II) complex. Bioorg Med Chem Lett 2016; 26:2730-4. [PMID: 27080177 DOI: 10.1016/j.bmcl.2016.03.091] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 03/11/2016] [Accepted: 03/25/2016] [Indexed: 10/22/2022]
Abstract
According to the previous studies, the anticancer activity of flavonoids could be enhanced when they are coordinated with transition metal ions. In this work, kaempferol-zinc(II) complex (kaempferol-Zn) was synthesized and its chemical properties were characterized by UV-VIS, FT-IR, (1)H NMR, elemental analysis, electrospray mass spectrometry (ES-MS) and fluorescence spectroscopy, which showed that the synthesized complex was coordinated with a Zn(II) ion via the 3-OH and 4-oxo groups. The anticancer effects of kaempferol-Zn and free kaempferol on human oesophageal cancer cell line (EC9706) were compared. MTT results demonstrated that the killing effect of kaempferol-Zn was two times higher than that of free kaempferol. Atomic force microscopy (AFM) showed the morphological and ultrastructural changes of cellular membrane induced by kaempferol-Zn at subcellular or nanometer level. Moreover, flow cytometric analysis indicated that kaempferol-Zn could induce apoptosis in EC9706 cells by regulating intracellular calcium ions. Collectively, all the data showed that kaempferol-Zn might be served as a kind of potential anticancer agent.
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Affiliation(s)
- Lv-Ying Tu
- Department of Chemistry, Jinan University, Guangzhou 510632, PR China
| | - Jiang Pi
- State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Macau 000853, PR China
| | - Hua Jin
- State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Macau 000853, PR China
| | - Ji-Ye Cai
- Department of Chemistry, Jinan University, Guangzhou 510632, PR China; State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Macau 000853, PR China
| | - Sui-Ping Deng
- Department of Chemistry, Jinan University, Guangzhou 510632, PR China.
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9
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Schillers H, Medalsy I, Hu S, Slade AL, Shaw JE. PeakForce Tapping resolves individual microvilli on living cells. J Mol Recognit 2016; 29:95-101. [PMID: 26414320 PMCID: PMC5054848 DOI: 10.1002/jmr.2510] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 08/17/2015] [Accepted: 08/18/2015] [Indexed: 12/18/2022]
Abstract
Microvilli are a common structure found on epithelial cells that increase the apical surface thus enhancing the transmembrane transport capacity and also serve as one of the cell's mechanosensors. These structures are composed of microfilaments and cytoplasm, covered by plasma membrane. Epithelial cell function is usually coupled to the density of microvilli and its individual size illustrated by diseases, in which microvilli degradation causes malabsorption and diarrhea. Atomic force microscopy (AFM) has been widely used to study the topography and morphology of living cells. Visualizing soft and flexible structures such as microvilli on the apical surface of a live cell has been very challenging because the native microvilli structures are displaced and deformed by the interaction with the probe. PeakForce Tapping® is an AFM imaging mode, which allows reducing tip-sample interactions in time (microseconds) and controlling force in the low pico-Newton range. Data acquisition of this mode was optimized by using a newly developed PeakForce QNM-Live Cell probe, having a short cantilever with a 17-µm-long tip that minimizes hydrodynamic effects between the cantilever and the sample surface. In this paper, we have demonstrated for the first time the visualization of the microvilli on living kidney cells with AFM using PeakForce Tapping. The structures observed display a force dependence representing either the whole microvilli or just the tips of the microvilli layer. Together, PeakForce Tapping allows force control in the low pico-Newton range and enables the visualization of very soft and flexible structures on living cells under physiological conditions.
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Affiliation(s)
- Hermann Schillers
- Institute of Physiology II, University of Münster, Robert-Koch-Str. 27b, Münster, 48149, Germany
| | - Izhar Medalsy
- Bruker Nano Surfaces Division, 112 Robin Hill Rd, Santa Barbara, CA, 93117, USA
| | - Shuiqing Hu
- Bruker Nano Surfaces Division, 112 Robin Hill Rd, Santa Barbara, CA, 93117, USA
| | - Andrea L Slade
- Bruker Nano Surfaces Division, 112 Robin Hill Rd, Santa Barbara, CA, 93117, USA
| | - James E Shaw
- Bruker Nano Surfaces Division, 112 Robin Hill Rd, Santa Barbara, CA, 93117, USA
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Stylianou A, Yova D, Alexandratou E. Investigation of the influence of UV irradiation on collagen thin films by AFM imaging. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2014; 45:455-68. [PMID: 25491851 DOI: 10.1016/j.msec.2014.09.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 08/21/2014] [Accepted: 09/08/2014] [Indexed: 01/06/2023]
Abstract
Collagen is the major fibrous extracellular matrix protein and due to its unique properties, it has been widely used as biomaterial, scaffold and cell-substrate. The aim of the paper was to use Atomic Force Microscopy (AFM) in order to investigate well-characterized collagen thin films after ultraviolet light (UV) irradiation. The films were also used as in vitro culturing substrates in order to investigate the UV-induced alterations to fibroblasts. A special attention was given in the alteration on collagen D-periodicity. For short irradiation times, spectroscopy (fluorescence/absorption) studies demonstrated that photodegradation took place and AFM imaging showed alterations in surface roughness. Also, it was highlighted that UV-irradiation had different effects when it was applied on collagen solution than on films. Concerning fibroblast culturing, it was shown that fibroblast behavior was affected after UV irradiation of both collagen solution and films. Furthermore, after a long irradiation time, collagen fibrils were deformed revealing that collagen fibrils are consisting of multiple shells and D-periodicity occurred on both outer and inner shells. The clarification of the effects of UV light on collagen and the induced modifications of cell behavior on UV-irradiated collagen-based surfaces will contribute to the better understanding of cell-matrix interactions in the nanoscale and will assist in the appropriate use of UV light for sterilizing and photo-cross-linking applications.
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Affiliation(s)
- Andreas Stylianou
- Biomedical Optics and Applied Biophysics Laboratory, Division of Electromagnetics, Electrooptics and Electronic Materials, School of Electrical and Computer Engineering, National Technical University of Athens, 9 Iroon Polytechniou, Athens 15780 Greece.
| | - Dido Yova
- Biomedical Optics and Applied Biophysics Laboratory, Division of Electromagnetics, Electrooptics and Electronic Materials, School of Electrical and Computer Engineering, National Technical University of Athens, 9 Iroon Polytechniou, Athens 15780 Greece
| | - Eleni Alexandratou
- Biomedical Optics and Applied Biophysics Laboratory, Division of Electromagnetics, Electrooptics and Electronic Materials, School of Electrical and Computer Engineering, National Technical University of Athens, 9 Iroon Polytechniou, Athens 15780 Greece
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11
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Ould-Moussa N, Safi M, Guedeau-Boudeville MA, Montero D, Conjeaud H, Berret JF. In vitro toxicity of nanoceria: effect of coating and stability in biofluids. Nanotoxicology 2013; 8:799-811. [PMID: 23914740 DOI: 10.3109/17435390.2013.831501] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Due to the increasing use of nanometric cerium oxide in applications, concerns about the toxicity of these particles have been raised and have resulted in a large number of studies. We report here on the interactions between 7 nm anionically charged cerium oxide particles and living mammalian cells. By a modification of the particle coating including low-molecular weight ligands and polymers, two generic behaviours are compared: particles coated with citrate ions that precipitate in biofluids and particles coated with poly(acrylic acid) that are stable and remain nanometric. We find that nanoceria covered with both coating agents are taken up by mouse fibroblasts and localized into membrane-bound compartments. However, flow cytometry and electron microscopy reveal that as a result of their precipitation, citrate-coated particles interact more strongly with cells. At cerium concentration above 1 mM, only citrate-coated nanoceria (and not particles coated with poly(acrylic acid)) display toxicity and moderate genotoxicity. The results demonstrate that the control of the surface chemistry of the particles and its ability to prevent aggregation can affect the toxicity of nanomaterials.
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Affiliation(s)
- Nawel Ould-Moussa
- Matière et Systèmes Complexes, UMR 7057 CNRS Université Denis Diderot Paris-VII, Bâtiment Condorcet , Paris , France
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12
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Yang H, Liu Y, Lu XL, Li XH, Zhang HG. Transmembrane transport of the Gαq protein carboxyl terminus imitation polypeptide GCIP-27. Eur J Pharm Sci 2013; 49:791-9. [PMID: 23748000 DOI: 10.1016/j.ejps.2013.05.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 05/22/2013] [Accepted: 05/28/2013] [Indexed: 12/22/2022]
Abstract
The Gαq protein carboxyl terminus imitation polypeptide (GCIP)-27 has been shown to affect cardiac hypertrophy and vascular remodeling in various models both in vitro and in vivo. Transport across the plasma membrane is a critical step in regulating the action of this peptide drug. This study was designed to explore the mechanisms underlying the transmembrane transport of GCIP-27. The peptide drug was labeled with fluorescein isothiocyanate (FITC), and measured in a time- and concentration-dependent manner using laser confocal microscopy. Various transport inhibitors, including energy and endocytosis inhibitors, were used to identify the factors that regulate its transmembrane transport. GCIP-27 transport was examined in cardiomyocytes, cardiac fibroblasts, vascular endothelial cells, vascular smooth muscle cells (VSMCs) and hepatocytes. Atomic force microscopy and scanning electron microscopy were used to determine the ultrastructure of the cardiomyocyte membranes. The results showed that GCIP-27 was transported through the plasmalemma in a time- and concentration-dependent manner. The rate of uptake and the level of GCIP-27 in the cells decreased significantly after treatment with energy inhibitors, methyl-ß-cyclodextrin chlorpromazine or heparin. GCIP-27 levels in VSMCs and cardiomyocytes were significantly greater than the levels observed in hepatocytes, cardiac fibroblasts and vascular endothelial cells. Treatment with GCIP-27 led to a marked increase in the surface roughness of the cellular membrane. In conclusion, the transmembrane transport of GCIP-27 is mediated by endocytosis, which requires energy, and GCIP-27 preferentially enters myocardial cells and VSMCs.
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Affiliation(s)
- Hua Yang
- Department of Pharmacology, College of Pharmacy, Third Military Medical University, Chongqing 40038, China
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13
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Antonio PD, Lasalvia M, Perna G, Capozzi V. Scale-independent roughness value of cell membranes studied by means of AFM technique. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:3141-8. [PMID: 22897980 DOI: 10.1016/j.bbamem.2012.08.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 07/31/2012] [Accepted: 08/02/2012] [Indexed: 12/25/2022]
Abstract
The roughness of cell membrane is a very interesting indicator of cell's health state. Atomic Force Microscopy allows us to investigate the roughness of cell membrane in great detail, but the obtained roughness value is scale-dependent, i.e. it strongly depends on measurement parameters, as scanning area and step size. The scale-dependence of the roughness value can be reduced by means of data filtration techniques, that are not standardized at nanometric scale, especially as far as biological data are concerned. In this work, a new method, based on the changes of values of some roughness parameter (root mean square roughness and skewness) as a function of filtration frequencies, has been implemented to optimize data filtering procedure in the calculation of cell membrane roughness. In this way, a root mean square roughness value independent of cell shape, membrane micro-irregularities and measurement parameters can be obtained. Moreover, different filtration frequencies selected with this method allow us to discriminate different surface regimes (nominal form, waviness and roughness) belonging to the raw cell profile, each one related to different features of the cell surface.
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Affiliation(s)
- Palma D Antonio
- Dipartimento di Medicina Clinica e Sperimentale, Università di Foggia, Viale Pinto, Italy
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Galimard A, Safi M, Ould-Moussa N, Montero D, Conjeaud H, Berret JF. Thirty-femtogram detection of iron in mammalian cells. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:2036-2044. [PMID: 22508659 DOI: 10.1002/smll.201102356] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 12/05/2011] [Indexed: 05/31/2023]
Abstract
Inorganic nanomaterials and particles with enhanced optical, mechanical, or magnetic attributes are currently being developed for a wide range of applications. Safety issues have developed however concerning their potential cyto- and genotoxicity. For in vivo and in vitro experimentations, recent developments have heightened the need for simple and facile methods to measure the amount of nanoparticles taken up by cells or tissues. In this work, a rapid and highly sensitive method for quantifying the uptake of iron oxide nanoparticles in mammalian cells is reported. The approach exploits the digestion of incubated cells with concentrated hydrochloric acid reactant and a colorimetric-based UV-visible absorption technique. The technique allows the detection of iron in cells over 4 decades in masses from 0.03 to 300 picograms per cell. Applied on particles of different surface chemistry and sizes, the protocol demonstrates that the coating is the key parameter in the nanoparticle/cell interactions. The data are corroborated by scanning and transmission electron microscopy, and the results stress the importance of resiliently adsorbed nanoparticles at the plasma membrane.
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Affiliation(s)
- Aymeric Galimard
- Matière et Systèmes Complexes, UMR 7057 CNRS Université Denis Diderot Paris-VII, Bâtiment Condorcet, 10 rue Alice Domon et Léonie Duquet, Paris, France
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15
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Hecht E, Thompson K, Frick M, Wittekindt OH, Dietl P, Mizaikoff B, Kranz C. Combined atomic force microscopy-fluorescence microscopy: analyzing exocytosis in alveolar type II cells. Anal Chem 2012; 84:5716-22. [PMID: 22694258 DOI: 10.1021/ac300775j] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hybrid atomic force microscopy (AFM)-fluorescence microscopy (FM) investigation of exocytosis in lung epithelial cells (ATII cells) allows the detection of individual exocytic events by FM, which can be simultaneously correlated to structural changes in individual cells by AFM. Exocytosis of lamellar bodies (LBs) represents a slow form of exocytosis found in many non-neuronal cells. Exocytosis of LBs, following stimulation with adenosine-5'-triphosphate (ATP) and phorbol 12-myristate 13-acetate (PMA), results in a cation influx via P2X(4) receptors at the site of LB fusion with the plasma membrane (PM), which should induce a temporary increase in cell height/volume. AFM measurements were performed in single-line scans across the cell surface. Five minutes after stimulation, ATII cells revealed a cell height and volume increase of 13.7% ± 4.1% and 15.9 ± 4.8% (N = 9), respectively. These transient changes depend on exocytic LB-PM fusion. Nonstimulated cells and cells lacking LB fusions did not show a significant change in cell height/volume (N = 8). In addition, a cell height decrease was observed in ATII cells stimulated by uridine-5'-triphosphate (UTP) and PMA, agonists inducing LB fusion with the PM, but not activation of P2X(4) receptors. The cell height and volume decreased by -8.6 ± 3.6% and -11.2 ± 3.9% (N = 5), respectively. Additionally, low force contact and dynamic mode AFM imaging of cell areas around the nucleus after stimulation with ATP/PMA was performed. Fused LBs are more pronounced in AFM topography images compared to nonfused LBs, concluding that different "dynamic states" of LBs or locations from the PM are captured during imaging.
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Affiliation(s)
- Elena Hecht
- Institute of Analytical and Bioanalytical Chemistry, University of Ulm, Ulm, Germany
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Miklavc P, Hecht E, Hobi N, Wittekindt OH, Dietl P, Kranz C, Frick M. Actin coating and compression of fused secretory vesicles are essential for surfactant secretion--a role for Rho, formins and myosin II. J Cell Sci 2012; 125:2765-74. [PMID: 22427691 DOI: 10.1242/jcs.105262] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Secretion of vesicular contents by exocytosis is a fundamental cellular process. Increasing evidence suggests that post-fusion events play an important role in determining the composition and quantity of the secretory output. In particular, regulation of fusion pore dilation and closure is considered a key regulator of the post-fusion phase. However, depending on the nature of the cargo, additional mechanisms might be essential to facilitate effective release. We have recently described that in alveolar type II (ATII) cells, lamellar bodies (LBs), which are secretory vesicles that store lung surfactant, are coated with actin following fusion with the plasma membrane. Surfactant, a lipoprotein complex, does not readily diffuse out of fused LBs following opening and dilation of the fusion pore. Using fluorescence microscopy, atomic force microscopy and biochemical assays, we present evidence that actin coating and subsequent contraction of the actin coat is essential to facilitate surfactant secretion. Latrunculin B prevents actin coating of fused LBs and inhibits surfactant secretion almost completely. Simultaneous imaging of the vesicle membrane and the actin coat revealed that contraction of the actin coat compresses the vesicle following fusion. This leads to active extrusion of vesicle contents. Initial actin coating of fused vesicles is dependent on activation of Rho and formin-dependent actin nucleation. Actin coat contraction is facilitated by myosin II. In summary, our data suggest that fusion pore opening and dilation itself is not sufficient for release of bulky vesicle cargos and that active extrusion mechanisms are required.
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Affiliation(s)
- Pika Miklavc
- Department of General Physiology, University of Ulm, Ulm, Germany
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17
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Hecht E, Knittel P, Felder E, Dietl P, Mizaikoff B, Kranz C. Combining atomic force-fluorescence microscopy with a stretching device for analyzing mechanotransduction processes in living cells. Analyst 2012; 137:5208-14. [DOI: 10.1039/c2an36001b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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