1
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Ouderkirk S, Sedley A, Ong M, Shifflet MR, Harkrider QC, Wright NT, Miller CJ. A Perspective on Developing Modeling and Image Analysis Tools to Investigate Mechanosensing Proteins. Integr Comp Biol 2023; 63:1532-1542. [PMID: 37558388 PMCID: PMC10755202 DOI: 10.1093/icb/icad107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/17/2023] [Accepted: 07/17/2023] [Indexed: 08/11/2023] Open
Abstract
The shift of funding organizations to prioritize interdisciplinary work points to the need for workflow models that better accommodate interdisciplinary studies. Most scientists are trained in a specific field and are often unaware of the kind of insights that other disciplines could contribute to solving various problems. In this paper, we present a perspective on how we developed an experimental pipeline between a microscopy and image analysis/bioengineering lab. Specifically, we connected microscopy observations about a putative mechanosensing protein, obscurin, to image analysis techniques that quantify cell changes. While the individual methods used are well established (fluorescence microscopy; ImageJ WEKA and mTrack2 programs; MATLAB), there are no existing best practices for how to integrate these techniques into a cohesive, interdisciplinary narrative. Here, we describe a broadly applicable workflow of how microscopists can more easily quantify cell properties (e.g., perimeter, velocity) from microscopy videos of eukaryotic (MDCK) adherent cells. Additionally, we give examples of how these foundational measurements can create more complex, customizable cell mechanics tools and models.
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Affiliation(s)
- Stephanie Ouderkirk
- Department of Chemistry, James Madison University, Harrisonburg, VA 22807, USA
| | - Alex Sedley
- Department of Engineering, James Madison University, Harrisonburg, VA 22807, USA
| | - Mason Ong
- Department of Engineering, James Madison University, Harrisonburg, VA 22807, USA
| | - Mary Ruth Shifflet
- Department of Chemistry, Bridgewater College, Bridgewater, VA 22812, USA
| | - Quinn C Harkrider
- Department of Chemistry, James Madison University, Harrisonburg, VA 22807, USA
| | - Nathan T Wright
- Department of Chemistry, James Madison University, Harrisonburg, VA 22807, USA
| | - Callie J Miller
- Department of Engineering, James Madison University, Harrisonburg, VA 22807, USA
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2
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Runel G, Lopez-Ramirez N, Chlasta J, Masse I. Biomechanical Properties of Cancer Cells. Cells 2021; 10:cells10040887. [PMID: 33924659 PMCID: PMC8069788 DOI: 10.3390/cells10040887] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/10/2021] [Accepted: 04/12/2021] [Indexed: 12/24/2022] Open
Abstract
Since the crucial role of the microenvironment has been highlighted, many studies have been focused on the role of biomechanics in cancer cell growth and the invasion of the surrounding environment. Despite the search in recent years for molecular biomarkers to try to classify and stratify cancers, much effort needs to be made to take account of morphological and nanomechanical parameters that could provide supplementary information concerning tissue complexity adaptation during cancer development. The biomechanical properties of cancer cells and their surrounding extracellular matrix have actually been proposed as promising biomarkers for cancer diagnosis and prognosis. The present review first describes the main methods used to study the mechanical properties of cancer cells. Then, we address the nanomechanical description of cultured cancer cells and the crucial role of the cytoskeleton for biomechanics linked with cell morphology. Finally, we depict how studying interaction of tumor cells with their surrounding microenvironment is crucial to integrating biomechanical properties in our understanding of tumor growth and local invasion.
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Affiliation(s)
- Gaël Runel
- Centre de Recherche en Cancérologie de Lyon, CNRS-UMR5286, INSREM U1052, Université de Lyon, F-69008 Lyon, France; (G.R.); (N.L.-R.)
- BioMeca, F-69008 Lyon, France;
| | - Noémie Lopez-Ramirez
- Centre de Recherche en Cancérologie de Lyon, CNRS-UMR5286, INSREM U1052, Université de Lyon, F-69008 Lyon, France; (G.R.); (N.L.-R.)
| | | | - Ingrid Masse
- Centre de Recherche en Cancérologie de Lyon, CNRS-UMR5286, INSREM U1052, Université de Lyon, F-69008 Lyon, France; (G.R.); (N.L.-R.)
- Correspondence:
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3
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Friedman D, Simmonds P, Hale A, Bere L, Hodson NW, White MRH, Davis DM. Natural killer cell immune synapse formation and cytotoxicity are controlled by tension of the target interface. J Cell Sci 2021; 134:jcs258570. [PMID: 33712452 PMCID: PMC8077183 DOI: 10.1242/jcs.258570] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 03/03/2021] [Indexed: 12/11/2022] Open
Abstract
Natural killer (NK) cells can kill infected or transformed cells via a lytic immune synapse. Diseased cells may exhibit altered mechanical properties but how this impacts NK cell responsiveness is unknown. We report that human NK cells were stimulated more effectively to secrete granzymes A and B, FasL (also known as FasLG), granulysin and IFNγ, by stiff (142 kPa) compared to soft (1 kPa) planar substrates. To create surrogate spherical targets of defined stiffness, sodium alginate was used to synthesise soft (9 kPa), medium (34 kPa) or stiff (254 kPa) cell-sized beads, coated with antibodies against activating receptor NKp30 (also known as NCR3) and the integrin LFA-1 (also known as ITGAL). Against stiff beads, NK cells showed increased degranulation. Polarisation of the microtubule-organising centre and lytic granules were impaired against soft targets, which instead resulted in the formation of unstable kinapses. Thus, by varying target stiffness to characterise the mechanosensitivity of immune synapses, we identify soft targets as a blind spot in NK cell recognition. This article has an associated First Person interview with the co-first authors of the paper.
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Affiliation(s)
- Daniel Friedman
- The Lydia Becker Institute, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility building, 46 Grafton Street, Manchester M13 9NT, United Kingdom
| | - Poppy Simmonds
- The Lydia Becker Institute, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility building, 46 Grafton Street, Manchester M13 9NT, United Kingdom
| | - Alexander Hale
- The Lydia Becker Institute, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility building, 46 Grafton Street, Manchester M13 9NT, United Kingdom
| | - Leoma Bere
- The Lydia Becker Institute, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility building, 46 Grafton Street, Manchester M13 9NT, United Kingdom
| | - Nigel W. Hodson
- BioAFM Facility, Faculty of Biology, Medicine and Health, Stopford Building, University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom
| | - Michael R. H. White
- Michael Smith Building, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Daniel M. Davis
- The Lydia Becker Institute, Faculty of Biology, Medicine and Health, University of Manchester, Core Technology Facility building, 46 Grafton Street, Manchester M13 9NT, United Kingdom
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4
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Bui VC, Nguyen TH. Direct monitoring of drug-induced mechanical response of individual cells by atomic force microscopy. J Mol Recognit 2020; 33:e2847. [PMID: 32212218 DOI: 10.1002/jmr.2847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 03/08/2020] [Accepted: 03/10/2020] [Indexed: 01/12/2023]
Abstract
Mechanical characteristics of individual cells play a vital role in many biological processes and are considered as indicators of the cells' states. Disturbances including methyl-β-cyclodextrin (MβCD) and cytochalasin D (cytoD) are known to significantly affect the state of cells, but little is known about the real-time response of single cells to these drugs in their physiological condition. Here, nanoindentation-based atomic force microscopy (AFM) was used to measure the elasticity of human embryonic kidney cells in the presence and absence of these pharmaceuticals. The results showed that depletion of cholesterol in the plasma membrane with MβCD resulted in cell stiffening whereas depolymerization of the actin cytoskeleton by cytoD resulted in cell softening. Using AFM for real-time measurements, we observed that cells mechanically responded right after these drugs were added. In more detail, the cell´s elasticity suddenly increased with increasing instability upon cholesterol extraction while it is rapidly decreased without changing cellular stability upon depolymerizing actin cytoskeleton. These results demonstrated that actin cytoskeleton and cholesterol contributed differently to the cell mechanical characteristics.
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Affiliation(s)
- Van-Chien Bui
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany.,ZIK HIKE, University of Greifswald, Greifswald, Germany
| | - Thi-Huong Nguyen
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany.,Institute for Bioprocessing and Analytical Measurement Techniques, Heilbad Heiligenstadt, Germany
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5
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Su X, Zhang L, Kang H, Zhang B, Bao G, Wang J. Mechanical, nanomorphological and biological reconstruction of early‑stage apoptosis in HeLa cells induced by cytochalasin B. Oncol Rep 2018; 41:928-938. [PMID: 30535459 PMCID: PMC6313055 DOI: 10.3892/or.2018.6921] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 11/22/2018] [Indexed: 12/29/2022] Open
Abstract
There is a growing interest in the fact that mechanical signals may be as important as biological signals in evaluating cell viability. To investigate the alterations in biomechanics, nanomorphology and biological apoptotic signals during early apoptosis, an apoptosis model was established for cervical cancer HeLa cells induced by cytochalasin B (CB). The cellular mechanical properties, geometry, morphology and expression of key apoptotic proteins were systematically analyzed. The findings indicated a marked decline in cellular elastic modulus and volume and a considerable increase in surface roughness occurring prior to the activation of biological apoptosis signals (such as phosphatidylserine exposure or activation of CD95/Fas). Moreover, the depolymerization of filamentous actin aggravated the intracellular crowding degree, which induced the redistribution of different-sized protein molecules and protrusions across the cell membrane arising from excluded volume interactions. Statistical analysis revealed that the disassembly of the actin cytoskeleton was negatively correlated with the cellular elastic modulus and volume, but was positively correlated with surface roughness and CD95/Fas activation. The results of the present study suggest that compared with biological signals, mechanical and geometrical reconstruction is more sensitive during apoptosis and the increase in cell surface roughness arises from the redistribution of biophysical molecules. These results contribute to our in-depth understanding of the apoptosis mechanisms of cancer cells mediated by cytochalasin B.
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Affiliation(s)
- Xuelian Su
- College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Ling Zhang
- Key Laboratory of Mechanics on Disaster and Environment in Western China, The Ministry of Education of China, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Hong Kang
- Key Laboratory of Mechanics on Disaster and Environment in Western China, The Ministry of Education of China, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Baoping Zhang
- Key Laboratory of Mechanics on Disaster and Environment in Western China, The Ministry of Education of China, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Guangjie Bao
- Key Laboratory of Stomatology of The State Ethnic Affairs Commission, Northwest Minzu University, Lanzhou, Gansu 730030, P.R. China
| | - Jizeng Wang
- College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
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6
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Barata D, Spennati G, Correia C, Ribeiro N, Harink B, van Blitterswijk C, Habibovic P, van Rijt S. Development of a shear stress-free microfluidic gradient generator capable of quantitatively analyzing single-cell morphology. Biomed Microdevices 2017; 19:81. [PMID: 28884359 PMCID: PMC5589786 DOI: 10.1007/s10544-017-0222-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Microfluidics, the science of engineering fluid streams at the micrometer scale, offers unique tools for creating and controlling gradients of soluble compounds. Gradient generation can be used to recreate complex physiological microenvironments, but is also useful for screening purposes. For example, in a single experiment, adherent cells can be exposed to a range of concentrations of the compound of interest, enabling high-content analysis of cell behaviour and enhancing throughput. In this study, we present the development of a microfluidic screening platform where, by means of diffusion, gradients of soluble compounds can be generated and sustained. This platform enables the culture of adherent cells under shear stress-free conditions, and their exposure to a soluble compound in a concentration gradient-wise manner. The platform consists of five serial cell culture chambers, all coupled to two lateral fluid supply channels that are used for gradient generation through a source-sink mechanism. Furthermore, an additional inlet and outlet are used for cell seeding inside the chambers. Finite element modeling was used for the optimization of the design of the platform and for validation of the dynamics of gradient generation. Then, as a proof-of-concept, human osteosarcoma MG-63 cells were cultured inside the platform and exposed to a gradient of Cytochalasin D, an actin polymerization inhibitor. This set-up allowed us to analyze cell morphological changes over time, including cell area and eccentricity measurements, as a function of Cytochalasin D concentration by using fluorescence image-based cytometry.
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Affiliation(s)
- David Barata
- Department of Tissue Regeneration, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands.,Department of Instructive Biomaterials Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, P.O. Box 616, 6200, MD, Maastricht, The Netherlands
| | - Giulia Spennati
- Department of Tissue Regeneration, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Cristina Correia
- Department of Tissue Regeneration, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Nelson Ribeiro
- Instituto de Engenharia Mecânica, Laboratório Associado de Energia, Transportes e Aeronáutica, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisbon, Portugal
| | - Björn Harink
- Department of Tissue Regeneration, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Clemens van Blitterswijk
- Department of Tissue Regeneration, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands.,Department of Complex Tissue Regeneration, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, P.O. Box 616, 6200, MD, Maastricht, The Netherlands
| | - Pamela Habibovic
- Department of Tissue Regeneration, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands.,Department of Instructive Biomaterials Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, P.O. Box 616, 6200, MD, Maastricht, The Netherlands
| | - Sabine van Rijt
- Department of Instructive Biomaterials Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, P.O. Box 616, 6200, MD, Maastricht, The Netherlands.
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7
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PKCα diffusion and translocation are independent of an intact cytoskeleton. Sci Rep 2017; 7:475. [PMID: 28352102 PMCID: PMC5428563 DOI: 10.1038/s41598-017-00560-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 03/03/2017] [Indexed: 01/04/2023] Open
Abstract
Translocation of cytosolic cPKC to the plasma membrane is a key event in their activation process but its exact nature is still unclear with particular dispute whether sole diffusion or additional active transport along the cell’s cytoskeleton contributes to cPKC’s dynamics. This was addressed by analyzing the recruitment behavior of PKCα while manipulating the cytoskeleton. Photolytic Ca2+ uncaging allowed us to quantify the kinetics of PKCα redistribution to the plasma membrane when fused to monomeric, dimeric and tetrameric fluorescence proteins. Results indicated that translocation kinetics were modulated by the state of oligomerization as expected for varying Stokes’ radii of the participating proteins. Following depolymerization of the microtubules and the actin filaments we found that Ca2+ induced membrane accumulation of PKCα was independent of the filamentous state of the cytoskeleton. Fusion of PKCα to the photo-convertible fluorescent protein Dendra2 enabled the investigation of PKCα-cytoskeleton interactions under resting conditions. Redistribution following spatially restricted photoconversion showed that the mobility of the fusion protein was independent of the state of the cytoskeleton. Our data demonstrated that in living cells neither actin filaments nor microtubules contribute to PKCα’s cytosolic mobility or Ca2+-induced translocation to the plasma membrane. Instead translocation is a solely diffusion-driven process.
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8
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Gavara N, Chadwick RS. Relationship between cell stiffness and stress fiber amount, assessed by simultaneous atomic force microscopy and live-cell fluorescence imaging. Biomech Model Mechanobiol 2015. [PMID: 26206449 PMCID: PMC4869747 DOI: 10.1007/s10237-015-0706-9] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Actomyosin stress fibers, one of the main components of the cell’s cytoskeleton, provide mechanical stability to adherent cells by applying and transmitting tensile forces onto the extracellular matrix (ECM) at the sites of cell–ECM adhesion. While it is widely accepted that changes in spatial and temporal distribution of stress fibers affect the cell’s mechanical properties, there is no quantitative knowledge on how stress fiber amount and organization directly modulate cell stiffness. We address this key open question by combining atomic force microscopy with simultaneous fluorescence imaging of living cells, and combine for the first time reliable quantitative parameters obtained from both techniques. We show that the amount of myosin and (to a lesser extent) actin assembled in stress fibers directly modulates cell stiffness in adherent mouse fibroblasts (NIH3T3). In addition, the spatial distribution of stress fibers has a second-order modulatory effect. In particular, the presence of either fibers located in the cell periphery, aligned fibers or thicker fibers gives rise to reinforced cell stiffness. Our results provide basic and significant information that will help design optimal protocols to regulate the mechanical properties of adherent cells via pharmacological interventions that alter stress fiber assembly or via micropatterning techniques that restrict stress fiber spatial organization.
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Affiliation(s)
- Núria Gavara
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, E1 3NS, UK.
| | - Richard S Chadwick
- Auditory Mechanics Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Building 10 Rm. 5D49, 10 Center Drive, MSC-1417, Bethesda, MD, 20892, USA
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9
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Glaubitz M, Medvedev N, Pussak D, Hartmann L, Schmidt S, Helm CA, Delcea M. A novel contact model for AFM indentation experiments on soft spherical cell-like particles. SOFT MATTER 2014; 10:6732-6741. [PMID: 25068646 DOI: 10.1039/c4sm00788c] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The use of the simple Hertz model for the analysis of Atomic Force Microscopy (AFM) force-distance curves measured on soft spherical cell-like particles leads to significant underestimations of the objects Young's modulus E. To correct this error, a mixed double contact model (based on the simple Hertz model and the Johnson-Kendall-Roberts (JKR) model) was derived. The model considers two independent particle deformation sites: (i) the upper part of the particle is deformed by the AFM indenter, (ii) the bottom part is deformed by the substrate, which is usually unnoticed. It becomes apparent that for soft particles even small forces between substrate and particle can influence the resulting force-distance curves. For instance we show, that a gravity-induced compression on the particle bottom side can have significant influence on the measurements. To highlight these observations, the deviation of the particle Young's modulus E between the simple Hertz model and our model is calculated. This error strongly depends on the ratio of the three involved radii: (i) the radius of the AFM indenter, (ii) the radius of the particle and (iii) the radius of the substrate as well as on the acting gravity force. Overall, the analysis suggests that for nanoscopic indenters the deviation is negligible, whereas the use of microscopic indenters results in significant errors that can be corrected via the presented model. This is important especially for very soft particles, since larger indenters can achieve higher signal to noise ratios. Furthermore, the applicability of the model was confirmed by indentation experiments on hydrogel microbeads. The mixed double contact model is applicable to a large range of indenter geometries and can be adapted for other contact models.
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Affiliation(s)
- Michael Glaubitz
- ZIK-HIKE - Zentrum für Innovationskompetenz "Humorale Immunreaktionen bei Kardiovaskulären Erkrankungen", Fleischmannstr. 42 - 44, D-17489 Greifswald, Germany.
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10
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Wang G, Mao W, Byler R, Patel K, Henegar C, Alexeev A, Sulchek T. Stiffness dependent separation of cells in a microfluidic device. PLoS One 2013; 8:e75901. [PMID: 24146787 PMCID: PMC3797716 DOI: 10.1371/journal.pone.0075901] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 08/17/2013] [Indexed: 12/18/2022] Open
Abstract
Abnormal cell mechanical stiffness can point to the development of various diseases including cancers and infections. We report a new microfluidic technique for continuous cell separation utilizing variation in cell stiffness. We use a microfluidic channel decorated by periodic diagonal ridges that compress the flowing cells in rapid succession. The compression in combination with secondary flows in the ridged microfluidic channel translates each cell perpendicular to the channel axis in proportion to its stiffness. We demonstrate the physical principle of the cell sorting mechanism and show that our microfluidic approach can be effectively used to separate a variety of cell types which are similar in size but of different stiffnesses, spanning a range from 210 Pa to 23 kPa. Atomic force microscopy is used to directly measure the stiffness of the separated cells and we found that the trajectories in the microchannel correlated to stiffness. We have demonstrated that the current processing throughput is 250 cells per second. This microfluidic separation technique opens new ways for conducting rapid and low-cost cell analysis and disease diagnostics through biophysical markers.
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Affiliation(s)
- Gonghao Wang
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Wenbin Mao
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Rebecca Byler
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Krishna Patel
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Caitlin Henegar
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Alexander Alexeev
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Todd Sulchek
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- * E-mail:
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11
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Sheets K, Wunsch S, Ng C, Nain AS. Shape-dependent cell migration and focal adhesion organization on suspended and aligned nanofiber scaffolds. Acta Biomater 2013; 9:7169-77. [PMID: 23567946 DOI: 10.1016/j.actbio.2013.03.042] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 03/20/2013] [Accepted: 03/29/2013] [Indexed: 01/13/2023]
Abstract
In the body, cells dynamically respond to chemical and mechanical cues from the extracellular matrix (ECM), yet precise mechanisms by which biophysical parameters (stiffness, topography and alignment) affect cell behavior remain unclear. Here, highly aligned and suspended multilayer polystyrene (PS) nanofiber scaffolds are used to study biophysical influences on focal adhesion complex (FAC) arrangement and associated migration behavior of mouse C2C12 cells arranged in specific shapes: spindle, parallel and polygonal. Furthermore, the role of cytoskeletal-altering drugs including blebbistatin, nocodazole and cytochalasin-D on FAC formation and migratory behavior is investigated. For the first time, this work reports that cells on suspended fiber networks, including cells with administered drugs, elongated along the fiber axes and developed longer (∼ 4×) and more concentrated FAC clusters compared to cells on flat PS control substrates. Additionally, substrate designs which topographically restrict sites of cell attachment and align adhesions were found to promote higher migration speeds (spindle: 52μmh(-1), parallel: 39μmh(-1), polygonal: 25μmh(-1), flat: 32μmh(-1)). This work demonstrates that suspended fiber topography-induced concentration of FACs along fiber axes generates increased migration potential as opposed to flat surfaces, which diffuse and randomly orient adhesions.
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12
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Su HT, Weng CC, Hsiao PJ, Chen LH, Kuo TL, Chen YW, Kuo KK, Cheng KH. Stem cell marker nestin is critical for TGF-β1-mediated tumor progression in pancreatic cancer. Mol Cancer Res 2013; 11:768-79. [PMID: 23552743 DOI: 10.1158/1541-7786.mcr-12-0511] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The stem cell marker nestin is an intermediate filament protein that plays an important role in cell integrity, migration, and differentiation. Nestin expression occurs in approximately one third of pancreatic ductal adenocarcinoma (PDAC), and its expression strongly correlates with tumor staging and metastasis. Little is known about the mechanisms by which nestin influences PDAC progression. Here, nestin overexpression in PDAC cells increased cell motility and drove phenotypic changes associated with the epithelial-mesenchymal transition (EMT) in vitro; conversely, knockdown of endogenous nestin expression reduced the migration rate and reverted cells to a more epithelial phenotype. Mouse xenograft studies showed that knockdown of nestin significantly reduced tumor incidence and volume. Nestin protein expression was associated with Smad4 status in PDAC cells; hence, nestin expression might be regulated by the TGF-β1/Smad4 pathway in PDAC. We examined nestin expression after TGF-β1 treatment in human pancreatic cancer PANC-1 and PANC-1 shSmad4 cells. The TGF-β1/Smad4 pathway induced nestin protein expression in PDAC cells in a Smad4-dependent manner. Moreover, increased nestin expression caused a positive feedback regulator of the TGF-β1 signaling system. In addition, hypoxia was shown to induce nestin expression in PDAC cells, and the hypoxia-induced expression of nestin is mediated by the TGF-β1/Smad4 pathway. Finally, the antimicrotubule inhibitors, cytochalasin D and withaferin A, exhibited anti-nestin activity; these inhibitors might be potential antimetastatic drugs. Our findings uncovered a novel role of nestin in regulating TGF-β1-induced EMT. Anti-nestin therapeutics may serve as a potential treatment for PDAC metastasis.
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Affiliation(s)
- Huei-Ting Su
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan 80424
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13
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Imaging living cells surface and quantifying its properties at high resolution using AFM in QI™ mode. Micron 2013; 48:26-33. [PMID: 23522742 DOI: 10.1016/j.micron.2013.02.003] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 02/06/2013] [Accepted: 02/07/2013] [Indexed: 11/21/2022]
Abstract
Since the last 10 years, AFM has become a powerful tool to study biological samples. However, the classical modes offered (imaging or tapping mode) often damage sample that are too soft or loosely immobilized. If imaging and mechanical properties are required, it requests long recording time as two different experiments must be conducted independently. In this study we compare the new QI™ mode against contact imaging mode and force volume mode, and we point out its benefit in the new challenges in biology on six different models: Escherichia coli, Candida albicans, Aspergillus fumigatus, Chinese hamster ovary cells and their isolated nuclei, and human colorectal tumor cells.
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Huber F, Schnauß J, Rönicke S, Rauch P, Müller K, Fütterer C, Käs J. Emergent complexity of the cytoskeleton: from single filaments to tissue. ADVANCES IN PHYSICS 2013; 62:1-112. [PMID: 24748680 PMCID: PMC3985726 DOI: 10.1080/00018732.2013.771509] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2011] [Revised: 01/11/2013] [Indexed: 05/17/2023]
Abstract
Despite their overwhelming complexity, living cells display a high degree of internal mechanical and functional organization which can largely be attributed to the intracellular biopolymer scaffold, the cytoskeleton. Being a very complex system far from thermodynamic equilibrium, the cytoskeleton's ability to organize is at the same time challenging and fascinating. The extensive amounts of frequently interacting cellular building blocks and their inherent multifunctionality permits highly adaptive behavior and obstructs a purely reductionist approach. Nevertheless (and despite the field's relative novelty), the physics approach has already proved to be extremely successful in revealing very fundamental concepts of cytoskeleton organization and behavior. This review aims at introducing the physics of the cytoskeleton ranging from single biopolymer filaments to multicellular organisms. Throughout this wide range of phenomena, the focus is set on the intertwined nature of the different physical scales (levels of complexity) that give rise to numerous emergent properties by means of self-organization or self-assembly.
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Affiliation(s)
- F. Huber
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| | - J. Schnauß
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| | - S. Rönicke
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| | - P. Rauch
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| | - K. Müller
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| | - C. Fütterer
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
| | - J. Käs
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
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Thickness profiling of formaldehyde-fixed cells by transmission-through-dye microscopy. Biotechniques 2011; 50:389-96. [PMID: 21781039 DOI: 10.2144/000113684] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 04/26/2011] [Indexed: 11/23/2022] Open
Abstract
Conventional light microscopy techniques are poorly suited for imaging the vertical cell dimension. This can be accomplished using transmission-through-dye (TTD) imaging, in which cell thickness is directly converted into image intensity in the presence of extracellular dye with strong absorption. We have previously described applications of TTD to living cells using the dye Acid Blue 9 (AB9) to generate contrast. In this work, we investigated the possibility of extending TTD to chemically fixed cells. This would depend on preservation of cell impermeability to the dye; by using a method based on fluorescence quenching, we found that formaldehyde-fixed cells remain impermeable to AB9. Fixation enables imaging of cell surfaces in the presence of high concentrations of AB9, bringing the vertical resolution to several nanometers per pixel; that is at least an order of magnitude better than resolution achievable with live cells. TTD images collected with high-NA objectives are often contaminated by Becke lines resulting from intracellular organelles, and we show how to distinguish them from features on the cell surface. Quantification of cell thickness and volume on fixed cells is also possible during the early stages of fixation; this can be useful, for example, for measuring volume kinetics following rapid introduction of a stimulus.
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A biophysical model of intracellular distribution and perinuclear accumulation of particulate matter. Biophys Chem 2011; 158:134-40. [DOI: 10.1016/j.bpc.2011.06.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 06/16/2011] [Accepted: 06/16/2011] [Indexed: 01/15/2023]
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Wolf-Ringwall AL, Winter PW, Liu J, Van Orden AK, Roess DA, Barisas BG. Restricted lateral diffusion of luteinizing hormone receptors in membrane microdomains. J Biol Chem 2011; 286:29818-27. [PMID: 21690095 DOI: 10.1074/jbc.m111.250969] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Single particle tracking was used to evaluate lateral motions of individual FLAG-tagged human luteinizing hormone (LH) receptors expressed on CHO cells and native LH receptors on both KGN human granulosa-derived tumor cells and M17 human neuroblastoma cells before and after exposure to human chorionic gonadotropin (hCG). Compared with LH receptors on untreated cells, LH receptors on cells treated with 100 nm hCG exhibit restricted lateral diffusion and are confined in small, nanometer-scale, membrane compartments. Similar to LH receptors labeled with Au-hCG, LH receptors labeled with gold-deglycosylated hCG, an hCG antagonist, also exhibit restricted lateral diffusion and are confined in nanoscale membrane compartments on KGN cells treated with 100 nm hCG. LH receptor point mutants lacking potential palmitoylation sites remain in large compartments despite treatment with 100 nm hCG as do LH receptors on cells treated with cytochalasin D. Finally, both polarization homotransfer fluorescence resonance energy transfer imaging and photon counting histogram analysis indicate that treatment with hCG induces aggregation of YFP-coupled LH receptors stably expressed on CHO cells. Taken together, our results demonstrate that binding of hCG induces aggregation of LH receptors within nanoscale, cell surface membrane compartments, that hCG binding also affects the lateral motions of antagonist binding LH receptors, and that receptor surface densities must be considered in evaluating the extent of hormone-dependent receptor aggregation.
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Affiliation(s)
- Amber L Wolf-Ringwall
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80523, USA
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