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Janshoff A. Viscoelasticity of basal plasma membranes and cortices derived from MDCK II cells. BIOPHYSICAL REPORTS 2021; 1:100024. [PMID: 36425463 PMCID: PMC9680774 DOI: 10.1016/j.bpr.2021.100024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 09/08/2021] [Indexed: 06/16/2023]
Abstract
The mechanical properties of cells are largely determined by the architecture and dynamics of their viscoelastic cortex, which consists of a contractile, cross-linked actin mesh attached to the plasma membrane via linker proteins. Measuring the mechanical properties of adherent, polarized epithelial cells is usually limited to the upper, i.e., apical side, of the cells because of their accessibility on culture dishes. Therefore, less is known about the viscoelastic properties of basal membranes. Here, I investigate the viscoelastic properties of basolateral membranes derived from polarized MDCK II epithelia in response to external deformation and compare them to living cells probed at the apical side. MDCK II cells were grown on porous surfaces to confluence, and the upper cell body was removed via a squirting-lysis protocol. The free-standing, defoliated basal membranes were subject to force indentation and relaxation experiments permitting a precise assessment of cortical viscoelasticity. A new theoretical framework to describe the force cycles is developed and applied to obtain the time-dependent area compressibility modulus of cell cortices from adherent cells. Compared with the viscoelastic response of living cells, the basolateral membranes are substantially less fluid and stiffer but obey to the same universal scaling law if excess area is taken correctly into account.
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Affiliation(s)
- Andreas Janshoff
- Department of Chemistry, Institute of Physical Chemistry, Göttingen
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2
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Ulloa LS, Perissinotto F, Rago I, Goldoni A, Santoro R, Pesce M, Casalis L, Scaini D. Carbon Nanotubes Substrates Alleviate Pro-Calcific Evolution in Porcine Valve Interstitial Cells. NANOMATERIALS 2021; 11:nano11102724. [PMID: 34685165 PMCID: PMC8538037 DOI: 10.3390/nano11102724] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 01/19/2023]
Abstract
The quest for surfaces able to interface cells and modulate their functionality has raised, in recent years, the development of biomaterials endowed with nanocues capable of mimicking the natural extracellular matrix (ECM), especially for tissue regeneration purposes. In this context, carbon nanotubes (CNTs) are optimal candidates, showing dimensions and a morphology comparable to fibril ECM constituents. Moreover, when immobilized onto surfaces, they demonstrated outstanding cytocompatibility and ease of chemical modification with ad hoc functionalities. In this study, we interface porcine aortic valve interstitial cells (pVICs) to multi-walled carbon nanotube (MWNT) carpets, investigating the impact of surface nano-morphology on cell properties. The results obtained indicate that CNTs significantly affect cell behavior in terms of cell morphology, cytoskeleton organization, and mechanical properties. We discovered that CNT carpets appear to maintain interfaced pVICs in a sort of “quiescent state”, hampering cell activation into a myofibroblasts-like phenotype morphology, a cellular evolution prodromal to Calcific Aortic Valve Disease (CAVD) and characterized by valve interstitial tissue stiffening. We found that this phenomenon is linked to CNTs’ ability to alter cell tensional homeostasis, interacting with cell plasma membranes, stabilizing focal adhesions and enabling a better strain distribution within cells. Our discovery contributes to shedding new light on the ECM contribution in modulating cell behavior and will open the door to new criteria for designing nanostructured scaffolds to drive cell functionality for tissue engineering applications.
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Affiliation(s)
- Luisa Severino Ulloa
- Dipartimento di Fisica, Università di Trieste, Piazzale Europa 1, 34127 Trieste, Italy; (L.S.U.); (F.P.); (I.R.)
| | - Fabio Perissinotto
- Dipartimento di Fisica, Università di Trieste, Piazzale Europa 1, 34127 Trieste, Italy; (L.S.U.); (F.P.); (I.R.)
| | - Ilaria Rago
- Dipartimento di Fisica, Università di Trieste, Piazzale Europa 1, 34127 Trieste, Italy; (L.S.U.); (F.P.); (I.R.)
| | - Andrea Goldoni
- Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, 34149 Trieste, Italy;
| | - Rosaria Santoro
- Unità di Ingegneria Tissutale Cardiovascolare, Centro Cardiologico Monzino, IRCCS, 20138 Milan, Italy; (R.S.); (M.P.)
| | - Maurizio Pesce
- Unità di Ingegneria Tissutale Cardiovascolare, Centro Cardiologico Monzino, IRCCS, 20138 Milan, Italy; (R.S.); (M.P.)
| | - Loredana Casalis
- Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, 34149 Trieste, Italy;
- Correspondence: (L.C.); (D.S.)
| | - Denis Scaini
- Area di Neuroscienze, Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, 34136 Trieste, Italy
- Faculty of Medicine, Imperial College London, London W12 0NN, UK
- Correspondence: (L.C.); (D.S.)
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Xu H, Gao J, Cai M, Chen J, Zhang Q, Li H, Wang H. Structural Mechanism Analysis of Orderly and Efficient Vesicle Transport by High-Resolution Imaging and Fluorescence Tracking. Anal Chem 2020; 92:6555-6563. [PMID: 32290652 DOI: 10.1021/acs.analchem.0c00197] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The orderly organelle interaction network is essential for normal biological activity of cells. However, the mechanism of orderly organelle interaction remains elusive. In this report, we analyzed the structure characteristics of the cell membrane, endocytic vesicles, and the Golgi membrane through a high-resolution imaging technique and further comprehensively investigated the vesicle-transport process via epidermal growth factor receptor endocytosis and a recycling pathway using a real-time fluorescence tracing method. Our data suggest that orderly vesicle transport is due to protein protrusion from the outer surface of endocytic vesicles and that full membrane fusion between homotypic endocytic vesicles is a result of the rough outer surface. Finally, the kiss-and-run method, which is utilized by endocytic vesicles to communicate with the trans-Golgi network (TGN) is attributed to a dense protein layer at the outer surface of the TGN. In summary, by combining static structural analysis with dynamic tracing, we elucidate the mechanism of orderly vesicle transport from the overall structural features of the membrane. This work provides insight into the structural mechanisms underlying vital biological processes involving organelle interactions at the molecular level.
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Affiliation(s)
- Haijiao Xu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P.R. China.,Graduate University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Jing Gao
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P.R. China
| | - Mingjun Cai
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P.R. China
| | - Junling Chen
- School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan, Hubei 430081, P.R. China
| | - Qingrong Zhang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P.R. China
| | - Hongru Li
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P.R. China.,University of Science and Technology of China, Hefei, Anhui 230026, P.R. China
| | - Hongda Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P.R. China.,Laboratory for Marine Biology and Biotechnology, Qing Dao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, P.R. China.,University of Science and Technology of China, Hefei, Anhui 230026, P.R. China
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4
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Tian Y, Wu Y, Liu L, He L, Gao J, Zhou L, Yu F, Yu S, Wang H. The structural characteristics of mononuclear-macrophage membrane observed by atomic force microscopy. J Struct Biol 2019; 206:314-321. [DOI: 10.1016/j.jsb.2019.04.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 03/09/2019] [Accepted: 04/01/2019] [Indexed: 01/26/2023]
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5
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Abstract
Atomic force microscopy (AFM) is a very versatile tool for studying biological samples at nanometer-scale resolution. The cell membrane plays a key role in compartmentalization, nutrient transportation, and signal transduction, while the structural feature of both sides of the membrane remains elusive. Here we describe our methods for the preparation of the cell membrane from the red blood cells and nucleated cells. High-resolution AFM topographs reveal substructural details of both sides of the cell membrane. The structure composition of cell membrane can be directly observed by time-lapse AFM and the positional information of membrane proteins can be located by molecular recognition.
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Affiliation(s)
- Mingjun Cai
- Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, People's Republic of China
| | - Hongda Wang
- Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, People's Republic of China.
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6
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Tian Y, Cai M, Xu H, Ding B, Hao X, Jiang J, Sun Y, Wang H. Atomic force microscopy of asymmetric membranes from turtle erythrocytes. Mol Cells 2014; 37:592-7. [PMID: 25134535 PMCID: PMC4145370 DOI: 10.14348/molcells.2014.0115] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 06/13/2014] [Accepted: 07/07/2014] [Indexed: 12/20/2022] Open
Abstract
The cell membrane provides critical cellular functions that rely on its elaborate structure and organization. The structure of turtle membranes is an important part of an ongoing study of erythrocyte membranes. Using a combination of atomic force microscopy and single-molecule force spectroscopy, we characterized the turtle erythrocyte membrane structure with molecular resolution in a quasi-native state. High-resolution images both leaflets of turtle erythrocyte membranes revealed a smooth outer membrane leaflet and a protein covered inner membrane leaflet. This asymmetry was verified by single-molecule force spectroscopy, which detects numerous exposed amino groups of membrane proteins in the inner membrane leaflet but much fewer in the outer leaflet. The asymmetric membrane structure of turtle erythrocytes is consistent with the semi-mosaic model of human, chicken and fish erythrocyte membrane structure, making the semi-mosaic model more widely applicable. From the perspective of biological evolution, this result may support the universality of the semi-mosaic model.
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Affiliation(s)
- Yongmei Tian
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022,
P.R. China
- University of Chinese Academy of Sciences, Beijing 100049,
P.R. China
| | - Mingjun Cai
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022,
P.R. China
| | - Haijiao Xu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022,
P.R. China
| | - Bohua Ding
- School of physics, Northeast Normal University, Changchun, Jilin 130024,
P.R. China
| | - Xian Hao
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022,
P.R. China
| | - Junguang Jiang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022,
P.R. China
| | - Yingchun Sun
- School of physics, Northeast Normal University, Changchun, Jilin 130024,
P.R. China
| | - Hongda Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022,
P.R. China
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7
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Zhao W, Tian Y, Cai M, Wang F, Wu J, Gao J, Liu S, Jiang J, Jiang S, Wang H. Studying the nucleated mammalian cell membrane by single molecule approaches. PLoS One 2014; 9:e91595. [PMID: 24806512 PMCID: PMC4012985 DOI: 10.1371/journal.pone.0091595] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Accepted: 02/12/2014] [Indexed: 01/24/2023] Open
Abstract
The cell membrane plays a key role in compartmentalization, nutrient transportation and signal transduction, while the pattern of protein distribution at both cytoplasmic and ectoplasmic sides of the cell membrane remains elusive. Using a combination of single-molecule techniques, including atomic force microscopy (AFM), single molecule force spectroscopy (SMFS) and stochastic optical reconstruction microscopy (STORM), to study the structure of nucleated cell membranes, we found that (1) proteins at the ectoplasmic side of the cell membrane form a dense protein layer (4 nm) on top of a lipid bilayer; (2) proteins aggregate to form islands evenly dispersed at the cytoplasmic side of the cell membrane with a height of about 10–12 nm; (3) cholesterol-enriched domains exist within the cell membrane; (4) carbohydrates stay in microdomains at the ectoplasmic side; and (5) exposed amino groups are asymmetrically distributed on both sides. Based on these observations, we proposed a Protein Layer-Lipid-Protein Island (PLLPI) model, to provide a better understanding of cell membrane structure, membrane trafficking and viral fusion mechanisms.
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Affiliation(s)
- Weidong Zhao
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yongmei Tian
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Mingjun Cai
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
| | - Feng Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
| | - Jiazhen Wu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jing Gao
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Shuheng Liu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
| | - Junguang Jiang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
| | - Shibo Jiang
- Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Shanghai Medical College, Fudan University, Shanghai, China
- Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
- * E-mail: (HW); (SJ)
| | - Hongda Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
- University of Chinese Academy of Sciences, Beijing, China
- * E-mail: (HW); (SJ)
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8
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García-Beltrán O, Yañez O, Caballero J, Galdámez A, Mena N, Nuñez MT, Cassels BK. Synthesis of coumarin derivatives as fluorescent probes for membrane and cell dynamics studies. Eur J Med Chem 2014; 76:79-86. [PMID: 24576613 DOI: 10.1016/j.ejmech.2014.02.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 11/13/2013] [Accepted: 02/08/2014] [Indexed: 01/07/2023]
Abstract
Three coumarin-derived fluorescent probes, 3-acetyl-7-[(6-bromohexyl)oxy]-2H-chromen-2-one (FM1), 7-[(6-bromohexyl)oxy]-4-methyl-2H-chromen-2-one (FM2) and ethyl 2-{7-[(6-bromohexyl)oxy]-2-oxo-2H-chromen-4-yl}acetate (FM3), are described, with their photophysical constants. The compounds were tested in preliminary studies employing epifluorescence microscopy demonstrating that they allow the imaging of human neuroblastoma SH-SY5Y cell membranes. The structure of FM3 was confirmed by X-ray crystallographic analysis. Molecular dynamics (MD) simulations were used to characterize the localization and interactions of the studied compounds with a lipid bilayer model of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC).
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Affiliation(s)
- Olimpo García-Beltrán
- Department of Chemistry, Faculty of Sciences, University of Chile, Santiago, Chile; Facultad de Ciencias Naturales y Matemáticas, Universidad de Ibagué, Carrera 22 Calle 67, Ibagué, Colombia.
| | - Osvaldo Yañez
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, 2 Norte 685, Casilla 721, Talca, Chile
| | - Julio Caballero
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, 2 Norte 685, Casilla 721, Talca, Chile
| | - Antonio Galdámez
- Department of Chemistry, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Natalia Mena
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Marco T Nuñez
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Bruce K Cassels
- Department of Chemistry, Faculty of Sciences, University of Chile, Santiago, Chile
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9
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Gudzenko T, Franz CM. Inverting adherent cells for visualizing ECM interactions at the basal cell side. Ultramicroscopy 2013; 128:1-9. [PMID: 23454470 DOI: 10.1016/j.ultramic.2012.12.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 12/10/2012] [Accepted: 12/21/2012] [Indexed: 10/27/2022]
Abstract
Interactions with the extracellular matrix (ECM) govern a wide range of cellular functions, including survival, migration and invasion. However, in adherent cells these interactions occur primarily on the basal cell side, making them inaccessible to high-resolution, surface-scanning imaging techniques such as atomic force microscopy (AFM) or scanning electron microscopy (SEM). Here we describe a fast and reliable method for inverting adherent cells, exposing the basal cell membrane for direct analysis by AFM or SEM in combination with fluorescence microscopy. Cells including their matrix adhesion sites remain intact during the inversion process and are transferred together with the complete array of basally associated ECM proteins. Molecular features of ECM proteins, such as the characteristic 67 nm collagen D-periodicity, are well preserved after inversion. To demonstrate the versatility of the method, we compared basal interactions of fibroblasts with fibrillar collagen I and fibronectin matrices. While fibroblasts remodel the fibronectin layer exclusively from above, they actively invade even thin collagen layers by contacting individual collagen nanofibrils both basally and apically through a network of cellular extensions. Cell-matrix entanglement coincides with enhanced cell spreading and flattening, indicating that nanoscale ECM interactions govern macroscopic changes in cell morphology. The presented cell inversion technique can thus provide novel insight into nanoscale cell-matrix interactions at the basal cell side.
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Affiliation(s)
- Tetyana Gudzenko
- DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology-KIT, Wolfgang-Gaede-Strasse 1a, 76131 Karlsruhe, Germany
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10
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Hallworth R, Nichols MG. Single molecule imaging approach to membrane protein stoichiometry. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2012; 18:771-780. [PMID: 22831749 PMCID: PMC3786598 DOI: 10.1017/s1431927612001195] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Recent technical advances have enabled the imaging of single fluorescent molecules. The application of single molecule visualization techniques has opened up new avenues of experimentation in biology at the molecular level. In this article, we review the application of single fluorescent molecule visualization and analysis to an important problem, that of subunit stoichiometry in membrane proteins, with particular emphasis on our approach. Single fluorescent molecules, coupled to fluorescent proteins, are localized in the membranes of cells. The molecules are then exposed to continuous low-level excitation until their fluorescent emissions reach background levels. The high sensitivity of modern instrumentation has enabled direct observations of discrete step decreases in the fluorescence of single molecules, which represent the bleaching of single fluorophores. By counting the number of steps over a large number of single molecules, an average step count is determined from which the stoichiometry is deduced using a binomial model. We examined the stoichiometry of a protein, prestin, that is central to mammalian hearing. We discuss how we prepared, identified, and imaged single molecules of prestin. The methodological considerations behind our approach are described and compared to similar procedures in other laboratories.
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Affiliation(s)
- Richard Hallworth
- Department of Biomedical Sciences, Creighton University School of Medicine, 2500 California Plaza, Omaha, NE 68178, USA.
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11
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Wu H, Oliver AE, Ngassam VN, Yee CK, Parikh AN, Yeh Y. Preparation, characterization, and surface immobilization of native vesicles obtained by mechanical extrusion of mammalian cells. Integr Biol (Camb) 2012; 4:685-92. [PMID: 22543681 DOI: 10.1039/c2ib20022h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Native vesicles or "reduced protocells" derived by mechanical extrusion concentrate selected plasma membrane components, while downsizing complexities of whole cells. We illustrate this technique, characterize the physical-chemical properties of these reduced configurations of whole cells, and demonstrate their surface immobilization and patternability. This simple detergent-free vesicularized membrane preparation should prove useful in fundamental studies of cellular membranes, and may provide a means to engineer therapeutic cells and enable high-throughput devices containing near-native, functional proteolipidic assemblies.
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Affiliation(s)
- Huawen Wu
- Department of Applied Science, University of California, Davis, One Shields Avenue, Davis, California 95616, USA
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12
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Tryoen-Tóth P, Chasserot-Golaz S, Tu A, Gherib P, Bader MF, Beaumelle B, Vitale N. HIV-1 Tat protein inhibits neurosecretion by binding to phosphatidylinositol (4,5) bisphosphate. J Cell Sci 2012. [DOI: 10.1242/jcs.111658] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
HIV-1 Tat enables viral transcription and is also actively released by infected cells. Extracellular Tat can enter uninfected cells and affect some cellular functions. Here, we examine the effects of Tat protein on the secretory activity of neuroendocrine cells. When added to the culture medium of chromaffin and PC12 cells, Tat was actively internalized and strongly impaired exocytosis as measured by carbon fiber amperometry and growth hormone (GH) release assay. Expression of Tat mutants that do not bind to phosphatidylinositol-(4,5)-bisphophate (PI(4,5)P2) did not affect secretion, and overexpression of phosphatidylinositol 4 phosphate 5-kinase (PIP5K), the major PI(4,5)P2 synthesizing enzyme, significantly rescued the Tat-induced inhibition of neurosecretion. This suggests that the inhibition of exocytosis may be the consequence of PI(4,5)P2 sequestration. Accordingly expression of Tat in PC12 cells interfered with the secretagogue-dependent recruitment of annexin A2 to the plasma membrane, a PI(4,5)P2-binding protein that promotes the formation of lipid microdomains that are required for exocytosis. In addition Tat significantly prevented the reorganization of the actin cytoskeleton necessary for the movement of secretory vesicles towards plasma membrane fusion sites. Thus, the capacity of extracellular Tat to enter neuroendocrine cells and sequester plasma membrane PI(4,5)P2 perturbs several PI(4,5)P2-dependent players of the exocytotic machinery, thereby affecting neurosecretion. We propose that Tat-induced inhibition of exocytosis is involved in the neuronal disorders associated with HIV-1 infection.
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Abstract
The unusual membrane motor protein prestin is essential for mammalian hearing and for the survival of cochlear outer hair cells. While prestin has been demonstrated to be a homooligomer, by Western blot and FRET analyses, the stoichiometry of self association is unclear. Prestin, coupled to the enhanced green fluorescent protein, was synthesized and membrane targeted in human embryonic kidney cells by plasmid transfection. Fragments of membrane containing immobilized fluorescent molecules were isolated by osmotic lysis. Diffraction-limited fluorescent spots consistent in size with single molecules were observed. Under continuous excitation, the spots bleached to background in sequential and approximately equal-amplitude steps. The average step count to background levels was 2.7. A binomial model of prestin oligomerization indicated that prestin was most likely a tetramer, and that a fraction of the green fluorescent protein molecules was dark. As a positive control, the same procedure was applied to cells transfected with plasmids coding for the human cyclic nucleotide-gated ion channel A3 subunit (again coupled to the enhanced green fluorescent protein), which is an obligate tetramer. The average step count for this molecule was also 2.7. This result implies that in cell membranes prestin oligomerizes to a tetramer.
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Affiliation(s)
- Richard Hallworth
- Dept. of Biomedical Sciences, Creighton Univ., 2500 California Plaza, Omaha, NE 68178, USA.
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15
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Lorenz B, Mey I, Steltenkamp S, Fine T, Rommel C, Müller MM, Maiwald A, Wegener J, Steinem C, Janshoff A. Elasticity mapping of pore-suspending native cell membranes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2009; 5:832-838. [PMID: 19242949 DOI: 10.1002/smll.200800930] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The mechanics of cellular membranes are governed by a non-equilibrium composite framework consisting of the semiflexible filamentous cytoskeleton and extracellular matrix proteins linked to the lipid bilayer. While elasticity information of plasma membranes has mainly been obtained from whole cell analysis, techniques that allow addressing local mechanical properties of cell membranes are desirable to learn how their lipid and protein composition is reflected in the elastic behavior on local length scales. Introduced here is an approach based on basolateral membranes of polar epithelial Madin-Darby canine kidney (MDCK) II cells, prepared on a highly ordered porous substrate that allows elastic mapping on a submicrometer-length scale. A strong correlation between the density of actin filaments and the measured membrane elasticity is found. Spatially resolved indentation experiments carried out with atomic force and fluorescence microscope permit relation of the supramolecular structure to the elasticity of cellular membranes. It is shown that the elastic response of the pore spanning cell membranes is governed by local bending modules rather than lateral tension.
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Affiliation(s)
- Bärbel Lorenz
- Institute of Physical Chemistry, University of Göttingen Tammannstr. 6, 37077 Göttingen, Germany
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16
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Abstract
The high sensitivity of mammalian hearing is achieved by amplification of the motion of the cochlear partition. The origin of this cochlear amplification is the elongation and contraction of outer hair cells (OHCs) in response to acoustical stimulation. This motility is made possible by a membrane protein embedded in the lateral membrane of OHCs. The gene of this protein has been identified and termed prestin. We, herein, present a method for observation by atomic force microscopy (AFM) of prestin expressed in the Chinese hamster ovary (CHO) cell plasma membrane. To obtain a stable sample for AFM imaging in liquid, we used as an example in the protocol provide here, CHO cells transfected with prestin or FLAG-tagged prestin, and untransfected CHO cells. The cells attached to a substrate were subjected to ultrasonic waves generated from a sonicator probe so that the inside-out plasma membranes remained on the substrate. Prestin was immunostained with mouse anti-FLAG primary antibody and FITC-conjugated goat anti-mouse IgG secondary antibody. The lipid of the plasma membrane was labeled with fluorescence probes. The cytoplasmic faces of the cells were then observed in liquid by the tapping mode of AFM at low and high magnifications. More particle-like structures 8-12 nm in diameter were observed in the plasma membranes of the prestin-transfected CHO cells than in those of the untransfected CHO cells. Since the difference between these two types of cells is due to the existence of prestin, such particle-like structures in the prestin-transfected CHO cells are possibly constituted by prestin.
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Affiliation(s)
- Michio Murakoshi
- Department of Bioengineering and Robotics, Graduate School of Engineering Tohoku University, Sendai, Japan
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Immune atomic force microscopy of prestin-transfected CHO cells using quantum dots. Pflugers Arch 2008; 457:885-98. [DOI: 10.1007/s00424-008-0560-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 07/07/2008] [Accepted: 07/14/2008] [Indexed: 11/26/2022]
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Murakoshi M, Gomi T, Iida K, Kumano S, Tsumoto K, Kumagai I, Ikeda K, Kobayashi T, Wada H. Imaging by atomic force microscopy of the plasma membrane of prestin-transfected Chinese hamster ovary cells. J Assoc Res Otolaryngol 2006; 7:267-78. [PMID: 16761115 PMCID: PMC2504612 DOI: 10.1007/s10162-006-0041-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Accepted: 04/26/2006] [Indexed: 11/27/2022] Open
Abstract
The high sensitivity of mammalian hearing is achieved by amplification of the motion of the cochlear partition. This cochlear amplification is thought to be generated by the elongation and contraction of outer hair cells (OHCs) in response to acoustical stimulation. This motility is made possible by a membrane protein embedded in the lateral membrane of OHCs. Although a fructose transporter, GLUT-5, was initially proposed to be this protein, a later study identified the gene of the motor protein distributed throughout the OHC plasma membrane. This protein has been named "prestin." However, although previous morphological studies by electron microscopy and atomic force microscopy (AFM) found the lateral wall of OHCs to be covered with 10-nm particles, believed to be motor proteins, it is unknown whether such particles consist only of prestin or are a complex of GLUT-5 and prestin molecules. To determine if the 10-nm particles are indeed constituted only of prestin, plasma membranes of prestin-transfected and untransfected Chinese hamster ovary (CHO) cells, which do not express GLUT-5, were observed by AFM. First, the cells attached to a substrate were sonicated so that only the plasma membrane remained on the substrate. The cytoplasmic face of the cell was observed by the tapping mode of the AFM in liquid. As a result, particle-like structures were recognized on the plasma membranes of both the prestin-transfected and untransfected CHO cells. Comparison of the difference in the frequency distribution of these structures between those two cells showed approximately 75% of the particle-like structures with a diameter of 8-12 nm in the prestin-transfected CHO cells to be possibly constituted only by prestin molecules. Our data suggest that the densely packed 10-nm particles observed on the OHC lateral wall are likely to be constituted only of prestin molecules.
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Affiliation(s)
- Michio Murakoshi
- Department of Bioengineering and Robotics, Tohoku University, 6-6-01 Aoba-yama, Sendai, 980-8579 Japan
| | - Takashi Gomi
- Department of Bioengineering and Robotics, Tohoku University, 6-6-01 Aoba-yama, Sendai, 980-8579 Japan
| | - Koji Iida
- Department of Bioengineering and Robotics, Tohoku University, 6-6-01 Aoba-yama, Sendai, 980-8579 Japan
| | - Shun Kumano
- Department of Bioengineering and Robotics, Tohoku University, 6-6-01 Aoba-yama, Sendai, 980-8579 Japan
| | - Kouhei Tsumoto
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8652 Japan
| | - Izumi Kumagai
- Department of Biomolecular Engineering, Tohoku University, 6-6-11 Aoba-yama, Sendai, 980-8579 Japan
| | - Katsuhisa Ikeda
- Department of Otorhinolaryngology, Juntendo University School of Medicine, 2-1-1 Hongo, Tokyo, 113-8421 Japan
| | - Toshimitsu Kobayashi
- Department of Otorhinolaryngology–Head and Neck Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Sendai, 980-8574 Japan
| | - Hiroshi Wada
- Department of Bioengineering and Robotics, Tohoku University, 6-6-01 Aoba-yama, Sendai, 980-8579 Japan
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19
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Chen H, Lü JH, Liang WQ, Huang YH, Zhang WJ, Zhang DB. Purification of the recombinant hepatitis B virus core antigen (rHBcAg) produced in the yeast Saccharomyces cerevisiae and comparative observation of its particles by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Micron 2004; 35:311-8. [PMID: 15006357 DOI: 10.1016/j.micron.2003.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2003] [Revised: 12/23/2003] [Accepted: 12/23/2003] [Indexed: 11/26/2022]
Abstract
Hepatitis B virus core antigen (HBcAg) gene (C gene) was expressed in Saccharomyces cerevisiae and the products (rHBcAg or core particles) were purified from a crude lysate of the yeast by three steps: Sephrose CL-4B chromatography, Sucrose step-gradient ultracentrifugation and CsCl-isopycnic ultracentrifugation. It has been observed that HBcAg was synthesized in yeast cells as a particle consisting of polypeptides with a molecular weight of 21.5 kDa (p21.5). Results of ELISA test and density analysis of CsCl-isopycnic ultracentrifugation indicated that the purified products (rHBcAg particles) with HBcAg antigenicity mainly located at the densities of 1.27 and 1.40 g ml(-1), respectively. Observation and analysis of the purified rHBcAg products by TEM indicated that rHBcAg peptides could mainly self-assemble into two size classes of core particles. The larger particles were approximately 30.1 nm and the smaller were approximately 21.5 nm in mean diameter. Further observation and analysis of the same rHBcAg (core) particles by AFM also indicated that rHBcAg (core) particles were similar to the native HBcAg (core) particles from infected human hepatocytes and mainly composed of two size classes of partides core. The larger particles were approximately 31.3 nm and the smaller were approximately 22.5 nm in mean diameter which was similar to the results obtained by TEM. All results from both TEM and AFM suggested that core particles (capsids) produced in S. cerevisiae possessed dimorphism.
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Affiliation(s)
- Heng Chen
- College of Life Science adn Biotechnology, Shanghai Jiaotong University, Shanghai, China.
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20
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Lesniewska E, Milhiet PE, Giocondi MC, Le Grimellec C. Atomic force microscope imaging of cells and membranes. Methods Cell Biol 2003; 68:51-65. [PMID: 12053740 DOI: 10.1016/s0091-679x(02)68004-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Eric Lesniewska
- Laboratory of Physics, National Center for Scientific Research, URA 5027, UFR Sciences et Techniques, 21078 Dijon, France
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21
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Schär-Zammaretti P, Ziegler U, Forster I, Groscurth P, Spichiger-Keller UE. Potassium-selective atomic force microscopy on ion-releasing substrates and living cells. Anal Chem 2002; 74:4269-74. [PMID: 12199601 DOI: 10.1021/ac025605n] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new method for simultaneous mapping of cell topography and ion fluxes was developed. A highly sensitive ion sensor system was generated by coating atomic force microscopy tips with a PVC layer containing valinomycin, an ionophore for potassium. The activity of specific ions was traced on artificial ion-releasing PVC substrates. A boundary potential was generated owing to the selective exchange of a specific ion between coated tip and ion-releasing substrate. The boundary potential was detectable as a force induced by ion-selective electrostatic interactions. The selectivity coefficient of valinomycin for potassium against sodium (K(K,Na)f) was -2.5 +/- 0.5. Potassium efflux was measured on living MDCK-F1 cells expressing BK(Ca) channels. We could demonstrate localized areas of high potassium concentrations at the cell surface. The potassium efflux could be reversibly inhibited by thapsigargin, which is known to inhibit the efflux of potassium from BK(Ca) channels by suppression of calcium ATPase.
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Affiliation(s)
- Prisca Schär-Zammaretti
- Center for Chemical Sensors/Biosensors and Bioanalytical Chemistry, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, Zürich.
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