1
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Fischer LS, Klingner C, Schlichthaerle T, Strauss MT, Böttcher R, Fässler R, Jungmann R, Grashoff C. Quantitative single-protein imaging reveals molecular complex formation of integrin, talin, and kindlin during cell adhesion. Nat Commun 2021; 12:919. [PMID: 33568673 PMCID: PMC7876120 DOI: 10.1038/s41467-021-21142-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 01/12/2021] [Indexed: 12/21/2022] Open
Abstract
Single-molecule localization microscopy (SMLM) enabling the investigation of individual proteins on molecular scales has revolutionized how biological processes are analysed in cells. However, a major limitation of imaging techniques reaching single-protein resolution is the incomplete and often unknown labeling and detection efficiency of the utilized molecular probes. As a result, fundamental processes such as complex formation of distinct molecular species cannot be reliably quantified. Here, we establish a super-resolution microscopy framework, called quantitative single-molecule colocalization analysis (qSMCL), which permits the identification of absolute molecular quantities and thus the investigation of molecular-scale processes inside cells. The method combines multiplexed single-protein resolution imaging, automated cluster detection, in silico data simulation procedures, and widely applicable experimental controls to determine absolute fractions and spatial coordinates of interacting species on a true molecular level, even in highly crowded subcellular structures. The first application of this framework allowed the identification of a long-sought ternary adhesion complex—consisting of talin, kindlin and active β1-integrin—that specifically forms in cell-matrix adhesion sites. Together, the experiments demonstrate that qSMCL allows an absolute quantification of multiplexed SMLM data and thus should be useful for investigating molecular mechanisms underlying numerous processes in cells. Single-molecule localisation microscopy is limited by low labeling and detection efficiencies of the molecular probes. Here the authors report a framework to obtain absolute molecular quantities on a true molecular scale; the data reveal a ternary adhesion complex underlying cell-matrix adhesion.
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Affiliation(s)
- Lisa S Fischer
- Department of Quantitative Cell Biology, Institute of Molecular Cell Biology, University of Münster, Münster, Germany.,Group of Molecular Mechanotransduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Christoph Klingner
- Department of Quantitative Cell Biology, Institute of Molecular Cell Biology, University of Münster, Münster, Germany.,Group of Molecular Mechanotransduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Thomas Schlichthaerle
- Faculty of Physics and Center for Nanoscience, LMU Munich, Munich, Germany.,Research Group Molecular Imaging and Bionanotechnology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Maximilian T Strauss
- Faculty of Physics and Center for Nanoscience, LMU Munich, Munich, Germany.,Research Group Molecular Imaging and Bionanotechnology, Max Planck Institute of Biochemistry, Martinsried, Germany.,Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Ralph Böttcher
- Department of Molecular Medicine, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Reinhard Fässler
- Department of Molecular Medicine, Max Planck Institute of Biochemistry, Martinsried, Germany.
| | - Ralf Jungmann
- Faculty of Physics and Center for Nanoscience, LMU Munich, Munich, Germany. .,Research Group Molecular Imaging and Bionanotechnology, Max Planck Institute of Biochemistry, Martinsried, Germany.
| | - Carsten Grashoff
- Department of Quantitative Cell Biology, Institute of Molecular Cell Biology, University of Münster, Münster, Germany. .,Group of Molecular Mechanotransduction, Max Planck Institute of Biochemistry, Martinsried, Germany.
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2
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Hamann S, Zhang J, Jang D, Hannaske A, Steinke L, Lausberg S, Pedrero L, Klingner C, Baenitz M, Steglich F, Krellner C, Geibel C, Brando M. Evolution from Ferromagnetism to Antiferromagnetism in Yb(Rh_{1-x}Co_{x})_{2}Si_{2}. Phys Rev Lett 2019; 122:077202. [PMID: 30848651 DOI: 10.1103/physrevlett.122.077202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Indexed: 06/09/2023]
Abstract
Yb(Rh_{1-x}Co_{x})_{2}Si_{2} is a model system to address two challenging problems in the field of strongly correlated electron systems. The first is the intriguing competition between ferromagnetic (FM) and antiferromagnetic (AFM) order when approaching a magnetic quantum critical point (QCP). The second is the occurrence of magnetic order along a very hard crystalline electric field (CEF) direction, i.e., along the one with the smallest available magnetic moment. Here, we present a detailed study of the evolution of the magnetic order in this system from a FM state with moments along the very hard c direction at x=0.27 towards the yet unknown magnetic state at x=0. We first observe a transition towards an AFM canted state with decreasing x and then to a pure AFM state. This confirms that the QCP in YbRh_{2}Si_{2} is AFM, but the phase diagram is very similar to those observed in some inherently FM systems like NbFe_{2} and CeRuPO, which suggests that the basic underlying instability might be FM. Despite the huge CEF anisotropy the ordered moment retains a component along the c axis also in the AFM state. The huge CEF anisotropy in Yb(Rh_{1-x}Co_{x})_{2}Si_{2} excludes that this hard-axis ordering originates from a competing exchange anisotropy as often proposed for other heavy-fermion systems. Instead, it points to an order-by-disorder based mechanism.
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Affiliation(s)
- S Hamann
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - J Zhang
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
- Center of Correlated Matter, Zheijiang University, CHN-310058 Hangzhou, China
| | - D Jang
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - A Hannaske
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - L Steinke
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
- Department of Physics, Texas A&M University, College Station, Texas 77843-4242, USA
| | - S Lausberg
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - L Pedrero
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - C Klingner
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - M Baenitz
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - F Steglich
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
- Center of Correlated Matter, Zheijiang University, CHN-310058 Hangzhou, China
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - C Krellner
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
- Institute of Physics, Goethe University Frankfurt, D-60438 Frankfurt am Main, Germany
| | - C Geibel
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - M Brando
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
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3
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Künstler ECS, Finke K, Günther A, Klingner C, Witte O, Bublak P. Motor-cognitive dual-task performance: effects of a concurrent motor task on distinct components of visual processing capacity. Psychol Res 2017; 82:177-185. [PMID: 29196834 PMCID: PMC5816117 DOI: 10.1007/s00426-017-0951-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 11/22/2017] [Indexed: 11/26/2022]
Abstract
Dual tasking, or the simultaneous execution of two continuous tasks, is frequently associated with a performance decline that can be explained within a capacity sharing framework. In this study, we assessed the effects of a concurrent motor task on the efficiency of visual information uptake based on the 'theory of visual attention' (TVA). TVA provides parameter estimates reflecting distinct components of visual processing capacity: perceptual threshold, visual processing speed, and visual short-term memory (VSTM) storage capacity. Moreover, goodness-of-fit values and bootstrapping estimates were derived to test whether the TVA-model is validly applicable also under dual task conditions, and whether the robustness of parameter estimates is comparable in single- and dual-task conditions. 24 subjects of middle to higher age performed a continuous tapping task, and a visual processing task (whole report of briefly presented letter arrays) under both single- and dual-task conditions. Results suggest a decline of both visual processing capacity and VSTM storage capacity under dual-task conditions, while the perceptual threshold remained unaffected by a concurrent motor task. In addition, goodness-of-fit values and bootstrapping estimates support the notion that participants processed the visual task in a qualitatively comparable, although quantitatively less efficient way under dual-task conditions. The results support a capacity sharing account of motor-cognitive dual tasking and suggest that even performing a relatively simple motor task relies on central attentional capacity that is necessary for efficient visual information uptake.
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Affiliation(s)
- E C S Künstler
- Hans Berger Department of Neurology, Jena University Hospital, Am Klinikum 1, 07747, Jena, Germany.
| | - K Finke
- Hans Berger Department of Neurology, Jena University Hospital, Am Klinikum 1, 07747, Jena, Germany
| | - A Günther
- Hans Berger Department of Neurology, Jena University Hospital, Am Klinikum 1, 07747, Jena, Germany
| | - C Klingner
- Hans Berger Department of Neurology, Jena University Hospital, Am Klinikum 1, 07747, Jena, Germany
| | - O Witte
- Hans Berger Department of Neurology, Jena University Hospital, Am Klinikum 1, 07747, Jena, Germany
| | - P Bublak
- Hans Berger Department of Neurology, Jena University Hospital, Am Klinikum 1, 07747, Jena, Germany
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4
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Wales P, Schuberth CE, Aufschnaiter R, Fels J, García-Aguilar I, Janning A, Dlugos CP, Schäfer-Herte M, Klingner C, Wälte M, Kuhlmann J, Menis E, Hockaday Kang L, Maier KC, Hou W, Russo A, Higgs HN, Pavenstädt H, Vogl T, Roth J, Qualmann B, Kessels MM, Martin DE, Mulder B, Wedlich-Söldner R. Calcium-mediated actin reset (CaAR) mediates acute cell adaptations. eLife 2016; 5. [PMID: 27919320 PMCID: PMC5140269 DOI: 10.7554/elife.19850] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 11/14/2016] [Indexed: 12/24/2022] Open
Abstract
Actin has well established functions in cellular morphogenesis. However, it is not well understood how the various actin assemblies in a cell are kept in a dynamic equilibrium, in particular when cells have to respond to acute signals. Here, we characterize a rapid and transient actin reset in response to increased intracellular calcium levels. Within seconds of calcium influx, the formin INF2 stimulates filament polymerization at the endoplasmic reticulum (ER), while cortical actin is disassembled. The reaction is then reversed within a few minutes. This Calcium-mediated actin reset (CaAR) occurs in a wide range of mammalian cell types and in response to many physiological cues. CaAR leads to transient immobilization of organelles, drives reorganization of actin during cell cortex repair, cell spreading and wound healing, and induces long-lasting changes in gene expression. Our findings suggest that CaAR acts as fundamental facilitator of cellular adaptations in response to acute signals and stress. DOI:http://dx.doi.org/10.7554/eLife.19850.001 Our skeleton plays a vital role in giving shape and structure to our body, it also allows us to make coordinated movements. Similarly, each cell contains a microscopic network of structures and supports called the cytoskeleton that helps cells to adopt specific shapes and is crucial for them to move around. Unlike our skeleton, which is relatively unchanging, the cytoskeleton of each cell constantly changes and adapts to the specific needs of the cell. One part of the cytoskeleton is a dense, flexible meshwork of fibers called the cortex that lies just beneath the surface of the cell. The cortex is constructed using a protein called actin, and many of these proteins join together to form each fiber. When cells need to adapt rapidly to an injury or other sudden changes in their environment they activate a so-called stress response. This response often begins with a rapid increase in the amount of calcium ions inside a cell, which can then trigger changes in actin organization. However, it is not clear how cells under stress are able to globally remodel their actin cytoskeleton without compromising stability and integrity of the cortex. Wales, Schuberth, Aufschnaiter et al. used a range of mammalian cells to investigate how actin responds to stress signals. All cells responded to the resulting influx of calcium ions by deconstructing large parts of the actin cortex and simultaneously forming actin filaments near the center of the cell. Wales, Schuberth, Aufschnaiter et al. termed this response calcium-mediated actin reset (CaAR), as it lasted for only a few minutes before the actin cortex reformed. The experiments show that a protein called INF2 controls CaAR by rapidly removing actin from the cortex and forming new filaments near a cell compartment called the endoplasmic reticulum. CaAR allows cells to rapidly and drastically alter the cortex in response to stress. The experiments also show that this sudden shift in actin can change the activity of certain genes, leading to longer-term effects on the cell. The findings of Wales, Schuberth, Aufschnaiter et al. suggest that calcium ions globally regulate the actin cytoskeleton and hence cell shape and movement under stress. This could be relevant for many important processes and conditions such as wound healing, inflammation and cancer. A future challenge will be to understand the role of CaAR in these processes. DOI:http://dx.doi.org/10.7554/eLife.19850.002
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Affiliation(s)
- Pauline Wales
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany
| | - Christian E Schuberth
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany
| | - Roland Aufschnaiter
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany
| | - Johannes Fels
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany
| | | | - Annette Janning
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany
| | - Christopher P Dlugos
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany.,Medical Clinic D, University Clinic of Muenster, Muenster, Germany
| | - Marco Schäfer-Herte
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany
| | - Christoph Klingner
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany.,AG Molecular Mechanotransduction, Max Planck Institute of Biochemistry, Munich, Germany
| | - Mike Wälte
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany
| | - Julian Kuhlmann
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany
| | - Ekaterina Menis
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany
| | - Laura Hockaday Kang
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany
| | - Kerstin C Maier
- Department of Biochemistry, University of Munich, Munich, Germany
| | - Wenya Hou
- Institute of Biochemistry I, Friedrich Schiller University Jena, Jena, Germany
| | - Antonella Russo
- Institute of Immunology, University of Münster, Münster, Germany
| | - Henry N Higgs
- Department of Biochemistry, Dartmouth Medical School, Hanover, United States
| | | | - Thomas Vogl
- Institute of Immunology, University of Münster, Münster, Germany
| | - Johannes Roth
- Institute of Immunology, University of Münster, Münster, Germany
| | - Britta Qualmann
- Institute of Biochemistry I, Friedrich Schiller University Jena, Jena, Germany
| | - Michael M Kessels
- Institute of Biochemistry I, Friedrich Schiller University Jena, Jena, Germany
| | - Dietmar E Martin
- Department of Biochemistry, University of Munich, Munich, Germany
| | - Bela Mulder
- Theory of Biological Matter, FOM Institute AMOLF, Amsterdam, Netherlands
| | - Roland Wedlich-Söldner
- Institute of Cell Dynamics and Imaging, University of Muenster, Muenster, Germany.,Cells-In-Motion Cluster of Excellence (EXC1003 - CiM), University of Münster, Muenster, Germany
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5
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Freikamp A, Mehlich A, Klingner C, Grashoff C. Investigating piconewton forces in cells by FRET-based molecular force microscopy. J Struct Biol 2016; 197:37-42. [PMID: 26980477 DOI: 10.1016/j.jsb.2016.03.011] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 03/11/2016] [Accepted: 03/12/2016] [Indexed: 11/16/2022]
Abstract
The ability of cells to sense and respond to mechanical forces is crucial for a wide range of developmental and pathophysiological processes. The molecular mechanisms underlying cellular mechanotransduction, however, are largely unknown because suitable techniques to measure mechanical forces across individual molecules in cells have been missing. In this article, we highlight advances in the development of molecular force sensing techniques and discuss our recently expanded set of FRET-based tension sensors that allows the analysis of mechanical forces with piconewton sensitivity in cells. In addition, we provide a theoretical framework for the design of additional tension sensor modules with adjusted force sensitivity.
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Affiliation(s)
- Andrea Freikamp
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, Martinsried D-82152, Germany
| | - Alexander Mehlich
- Technical University of Munich, Physics Department E22, Garching D-85748, Germany
| | - Christoph Klingner
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, Martinsried D-82152, Germany
| | - Carsten Grashoff
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, Martinsried D-82152, Germany.
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6
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Austen K, Ringer P, Mehlich A, Chrostek-Grashoff A, Kluger C, Klingner C, Sabass B, Zent R, Rief M, Grashoff C. Extracellular rigidity sensing by talin isoform-specific mechanical linkages. Nat Cell Biol 2015; 17:1597-606. [PMID: 26523364 PMCID: PMC4662888 DOI: 10.1038/ncb3268] [Citation(s) in RCA: 234] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 10/08/2015] [Indexed: 12/13/2022]
Abstract
The ability of cells to adhere and sense differences in tissue stiffness is crucial for organ development and function. The central mechanisms by which adherent cells detect extracellular matrix compliance, however, are still unknown. Using two single-molecule-calibrated biosensors that allow the analysis of a previously inaccessible but physiologically highly relevant force regime in cells, we demonstrate that the integrin activator talin establishes mechanical linkages following cell adhesion, which are indispensable for cells to probe tissue stiffness. Talin linkages are exposed to a range of piconewton forces and bear, on average, 7-10 pN during cell adhesion depending on their association with F-actin and vinculin. Disruption of talin's mechanical engagement does not impair integrin activation and initial cell adhesion but prevents focal adhesion reinforcement and thus extracellular rigidity sensing. Intriguingly, talin mechanics are isoform specific so that expression of either talin-1 or talin-2 modulates extracellular rigidity sensing.
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Affiliation(s)
- Katharina Austen
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, Martinsried D-82152, Germany
| | - Pia Ringer
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, Martinsried D-82152, Germany
| | - Alexander Mehlich
- Technical University of Munich, Physics Department E22, Garching D-85748, Germany
| | - Anna Chrostek-Grashoff
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, Martinsried D-82152, Germany
| | - Carleen Kluger
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, Martinsried D-82152, Germany
| | - Christoph Klingner
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, Martinsried D-82152, Germany
| | - Benedikt Sabass
- Princeton University, Department of Mechanical & Aerospace Engineering, Princeton, NJ 08544, USA
| | - Roy Zent
- Vanderbilt University, Division of Nephrology, Department of Medicine, Nashville, Tennessee 37232, USA
| | - Matthias Rief
- Technical University of Munich, Physics Department E22, Garching D-85748, Germany
- Munich Centre for Integrated Protein Science, Munich D-81377, Germany
| | - Carsten Grashoff
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, Martinsried D-82152, Germany
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7
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Marel AK, Zorn M, Klingner C, Wedlich-Söldner R, Frey E, Rädler JO. Flow and diffusion in channel-guided cell migration. Biophys J 2015; 107:1054-1064. [PMID: 25185541 DOI: 10.1016/j.bpj.2014.07.017] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 07/02/2014] [Accepted: 07/09/2014] [Indexed: 01/19/2023] Open
Abstract
Collective migration of mechanically coupled cell layers is a notable feature of wound healing, embryonic development, and cancer progression. In confluent epithelial sheets, the dynamics have been found to be highly heterogeneous, exhibiting spontaneous formation of swirls, long-range correlations, and glass-like dynamic arrest as a function of cell density. In contrast, the flow-like properties of one-sided cell-sheet expansion in confining geometries are not well understood. Here, we studied the short- and long-term flow of Madin-Darby canine kidney (MDCK) cells as they moved through microchannels. Using single-cell tracking and particle image velocimetry (PIV), we found that a defined averaged stationary cell current emerged that exhibited a velocity gradient in the direction of migration and a plug-flow-like profile across the advancing sheet. The observed flow velocity can be decomposed into a constant term of directed cell migration and a diffusion-like contribution that increases with density gradient. The diffusive component is consistent with the cell-density profile and front propagation speed predicted by the Fisher-Kolmogorov equation. To connect diffusion-mediated transport to underlying cellular motility, we studied single-cell trajectories and occurrence of vorticity. We discovered that the directed large-scale cell flow altered fluctuations in cellular motion at short length scales: vorticity maps showed a reduced frequency of swirl formation in channel flow compared with resting sheets of equal cell density. Furthermore, under flow, single-cell trajectories showed persistent long-range, random-walk behavior superimposed on drift, whereas cells in resting tissue did not show significant displacements with respect to neighboring cells. Our work thus suggests that active cell migration manifests itself in an underlying, spatially uniform drift as well as in randomized bursts of short-range correlated motion that lead to a diffusion-mediated transport.
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Affiliation(s)
- Anna-Kristina Marel
- Fakultät für Physik, Ludwig Maximilians Universität, München, Germany; Center for NanoScience, Ludwig Maximilians Universität, München, Germany; Nanosystems Initiative Munich, München, Germany
| | - Matthias Zorn
- Fakultät für Physik, Ludwig Maximilians Universität, München, Germany; Center for NanoScience, Ludwig Maximilians Universität, München, Germany
| | | | | | - Erwin Frey
- Fakultät für Physik, Ludwig Maximilians Universität, München, Germany; Center for NanoScience, Ludwig Maximilians Universität, München, Germany; Arnold Sommerfeld Center, Ludwig Maximilians Universität, München, Germany; Nanosystems Initiative Munich, München, Germany
| | - Joachim O Rädler
- Fakultät für Physik, Ludwig Maximilians Universität, München, Germany; Center for NanoScience, Ludwig Maximilians Universität, München, Germany; Nanosystems Initiative Munich, München, Germany.
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8
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Klingner C, Cherian AV, Fels J, Diesinger PM, Aufschnaiter R, Maghelli N, Keil T, Beck G, Tolić-Nørrelykke IM, Bathe M, Wedlich-Soldner R. Isotropic actomyosin dynamics promote organization of the apical cell cortex in epithelial cells. ACTA ACUST UNITED AC 2015; 207:107-21. [PMID: 25313407 PMCID: PMC4195824 DOI: 10.1083/jcb.201402037] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Apical membrane organization of nonconfluent epithelial cells is driven by a dynamic network of actin and myosin II filaments. Although cortical actin plays an important role in cellular mechanics and morphogenesis, there is surprisingly little information on cortex organization at the apical surface of cells. In this paper, we characterize organization and dynamics of microvilli (MV) and a previously unappreciated actomyosin network at the apical surface of Madin–Darby canine kidney cells. In contrast to short and static MV in confluent cells, the apical surfaces of nonconfluent epithelial cells (ECs) form highly dynamic protrusions, which are often oriented along the plane of the membrane. These dynamic MV exhibit complex and spatially correlated reorganization, which is dependent on myosin II activity. Surprisingly, myosin II is organized into an extensive network of filaments spanning the entire apical membrane in nonconfluent ECs. Dynamic MV, myosin filaments, and their associated actin filaments form an interconnected, prestressed network. Interestingly, this network regulates lateral mobility of apical membrane probes such as integrins or epidermal growth factor receptors, suggesting that coordinated actomyosin dynamics contributes to apical cell membrane organization.
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Affiliation(s)
- Christoph Klingner
- Cellular Dynamics and Cell Patterning and Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany Institute of Cell Dynamics and Imaging and Cells-In-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, 48149 Münster, Germany Institute of Cell Dynamics and Imaging and Cells-In-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, 48149 Münster, Germany
| | - Anoop V Cherian
- Cellular Dynamics and Cell Patterning and Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Johannes Fels
- Institute of Cell Dynamics and Imaging and Cells-In-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, 48149 Münster, Germany Institute of Cell Dynamics and Imaging and Cells-In-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, 48149 Münster, Germany
| | - Philipp M Diesinger
- Laboratory for Computational Biology & Biophysics, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Roland Aufschnaiter
- Cellular Dynamics and Cell Patterning and Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany Institute of Cell Dynamics and Imaging and Cells-In-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, 48149 Münster, Germany Institute of Cell Dynamics and Imaging and Cells-In-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, 48149 Münster, Germany
| | - Nicola Maghelli
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Thomas Keil
- Cellular Dynamics and Cell Patterning and Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Gisela Beck
- Cellular Dynamics and Cell Patterning and Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany Institute of Cell Dynamics and Imaging and Cells-In-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, 48149 Münster, Germany Institute of Cell Dynamics and Imaging and Cells-In-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, 48149 Münster, Germany
| | - Iva M Tolić-Nørrelykke
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany Division of Molecular Biology, Ruđer Bošković Institute, 10000 Zagreb, Croatia
| | - Mark Bathe
- Laboratory for Computational Biology & Biophysics, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Roland Wedlich-Soldner
- Cellular Dynamics and Cell Patterning and Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany Institute of Cell Dynamics and Imaging and Cells-In-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, 48149 Münster, Germany Institute of Cell Dynamics and Imaging and Cells-In-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, 48149 Münster, Germany
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Günther A, Llompart-Pou J, Klingner C, Witte O, Terborg C. Sonografische Methoden in der Hirntoddiagnostik. KLIN NEUROPHYSIOL 2014. [DOI: 10.1055/s-0034-1387208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- A. Günther
- Hans-Berger-Klinik für Neurologie, Universitätsklinikum Jena
| | - J. Llompart-Pou
- Intensive Care Unit, Hospital Universitari Son Espases, Palma de Mallorca, Illes Balears, Spanien
| | - C. Klingner
- Hans-Berger-Klinik für Neurologie, Universitätsklinikum Jena
| | - O. Witte
- Hans-Berger-Klinik für Neurologie, Universitätsklinikum Jena
| | - C. Terborg
- Klinik für Neurologie, Asklepios-Klinik St. Georg, Hamburg
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Lausberg S, Hannaske A, Steppke A, Steinke L, Gruner T, Pedrero L, Krellner C, Klingner C, Brando M, Geibel C, Steglich F. Doped YbRh2Si2: not only ferromagnetic correlations but ferromagnetic order. Phys Rev Lett 2013; 110:256402. [PMID: 23829749 DOI: 10.1103/physrevlett.110.256402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 05/08/2013] [Indexed: 06/02/2023]
Abstract
YbRh2Si2 is a prototypical system for studying unconventional antiferromagnetic quantum criticality. However, ferromagnetic correlations are present which can be enhanced via isoelectronic cobalt substitution for rhodium in Yb(Rh(1-x)Co(x))2Si2. So far, the magnetic order with increasing x was believed to remain antiferromagnetic. Here, we present the discovery of ferromagnetism for x = 0.27 below T(C) = 1.30 K in single crystalline samples. Unexpectedly, ordering occurs along the c axis, the hard crystalline electric field direction, where the g factor is an order of magnitude smaller than in the basal plane. Although the spontaneous magnetization is only 0.1 μB/Yb it corresponds to the full expected saturation moment along c taking into account partial Kondo screening.
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Affiliation(s)
- S Lausberg
- Max-Planck-Institute for Chemical Physics of Solids, D-01187 Dresden, Germany.
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11
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Steglich F, Arndt J, Stockert O, Friedemann S, Brando M, Klingner C, Krellner C, Geibel C, Wirth S, Kirchner S, Si Q. Magnetism, f-electron localization and superconductivity in 122-type heavy-fermion metals. J Phys Condens Matter 2012; 24:294201. [PMID: 22773300 DOI: 10.1088/0953-8984/24/29/294201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Both CeCu2Si2 and YbRh2Si2 crystallize in the tetragonal ThCr2Si2 crystal structure. Recent neutron-scattering results on normal-state CeCu2Si2 reveal a slowing down of the quasielastic response which complies with the scaling expected for a quantum critical point (QCP) of itinerant, i.e., three-dimensional spin-density-wave (SDW), type. This interpretation is in full agreement with the non-Fermi-liquid behavior observed in transport and thermodynamic measurements. The momentum dependence of the magnetic excitation spectrum reveals two branches of an overdamped dispersive mode whose coupling to the heavy charge carriers is strongly retarded. These overdamped spin fluctuations are considered to be the driving force for superconductivity in CeCu2Si2 (Tc = 600 mK). The weak antiferromagnet YbRh2Si2 (TN = 70 mK) exhibits a magnetic-field-induced QCP at BN = 0.06 T (B⊥c). There is no indication of superconductivity down to T = 10 mK. The magnetic QCP appears to concur with a breakdown of the Kondo effect. Doping-induced variations of the average unit-cell volume result in a detachment of the magnetic and electronic instabilities. A comparison of the properties of these isostructural compounds suggests that 3D SDW QCPs are favorable for unconventional superconductivity. The question whether a Kondo-breakdown QCP may also give rise to superconductivity, however, remains to be clarified.
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Affiliation(s)
- F Steglich
- Max Planck Institute for Chemical Physics of Solids, Noethnitzer Straße 40, 01187 Dresden, Germany.
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Diesinger P, Cherian A, Klingner C, Wedlich-Soldner R, Bathe M. Structure and Dynamics of Epithelial Cell Cortical Actomyosin Networks. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.2630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Leib J, Braun J, Schilling A, Klingner C, Seyfert S, Vollmann W, Gedat E, Bernarding J. In vivo 1 H magnetic resonance spectroscopy of rat brain after valproate administration. Neuroradiology 2004; 46:363-7. [PMID: 15045495 DOI: 10.1007/s00234-004-1182-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2003] [Accepted: 01/29/2004] [Indexed: 11/26/2022]
Abstract
Previous studies have shown that valproate is detectable in vitro by 1H magnetic resonance spectroscopy (MRS) at 1.5 T, whereas in patients on valproate monotherapy, no significant dose-dependent valproate signal could be seen. To investigate whether an increased signal-to-noise ratio as provided by higher valproate doses and increased magnetic field strength would enable detection of valproate in vivo, six Wistar rats were examined using volume-selective 1H MRS at 2.34 T. The spectra were analyzed by fitting a linear superposition of the basis spectra of valproate, brain metabolites, and simulated lipid signals. The analysis revealed no significant signal contributions after valproate administration of up to 330 mg/kg body weight. To analyze how underlying mechanisms, such as potential drug interactions with macromolecules, may affect the valproate signal, additional in vitro spectra of valproate were measured before and after adding albumin. The spectra exhibited a strong decrease of the valproate signal with increasing albumin concentration. The results support the hypothesis that in vivo valproate is bound to a high degree to macromolecules and will therefore not be detectable by 1H MRS.
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Affiliation(s)
- J Leib
- Department of Medical Informatics, Otto-von-Guericke University Magdeburg, Leipziger Strasse 44, 39120, Magdeburg, Germany
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