scholarly journals Protrusion force microscopy reveals oscillatory force generation and mechanosensing activity of human macrophage podosomes

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Anna Labernadie ◽  
Anaïs Bouissou ◽  
Patrick Delobelle ◽  
Stéphanie Balor ◽  
Raphael Voituriez ◽  
...  
Keyword(s):  
Force Generation ◽  
Human Macrophage ◽  
Force Microscopy ◽  
Oscillatory Force

scholarly journals Combined Confocal and Atomic Force Microscopy Studies of Force Transmission, Force Generation and Strain Dynamics in Living Cells

2013 ◽  
Vol 19 (S2) ◽  
pp. 32-33
Author(s):  
A. Pelling
Keyword(s):  
Atomic Force Microscopy ◽  
Living Cells ◽  
Force Generation ◽  
Force Transmission ◽  
Force Microscopy ◽  
Atomic Force

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

scholarly journals Phagocytic 'teeth' and myosin-II 'jaw' power target constriction during phagocytosis

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Daan Vorselen ◽  
Sarah R Barger ◽  
Yifan Wang ◽  
Wei Cai ◽  
Julie A Theriot ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Traction Force ◽  
Light Sheet ◽  
Force Generation ◽  
Actin Dynamics ◽  
Force Microscopy ◽  
Light Sheet Microscopy ◽  
Macrophage Phagocytosis ◽  
Actin Protrusions

Phagocytosis requires rapid actin reorganization and spatially controlled force generation to ingest targets ranging from pathogens to apoptotic cells. How actomyosin activity directs membrane extensions to engulf such diverse targets remains unclear. Here, we combine lattice light-sheet microscopy (LLSM) with microparticle traction force microscopy (MP-TFM) to quantify actin dynamics and subcellular forces during macrophage phagocytosis. We show that spatially localized forces leading to target constriction are prominent during phagocytosis of antibody-opsonized targets. This constriction is largely driven by Arp2/3-mediated assembly of discrete actin protrusions containing myosin 1e and 1f ('teeth') that appear to be interconnected in a ring-like organization. Contractile myosin-II activity contributes to late-stage phagocytic force generation and progression, supporting a specific role in phagocytic cup closure. Observations of partial target eating attempts and sudden target release via a popping mechanism suggest that constriction may be critical for resolving complex in vivo target encounters. Overall, our findings present a phagocytic cup-shaping mechanism that is distinct from cytoskeletal remodeling in 2D cell motility and may contribute to mechanosensing and phagocytic plasticity.

scholarly journals Crosstalk between myosin II and formin functions in the regulation of force generation and actomyosin dynamics in stress fibers

2021 ◽  
Author(s):  
Yukako Nishimura ◽  
Shidong Shi ◽  
Qingsen Li ◽  
Alexander D. Bershadsky ◽  
Virgile Viasnoff
Keyword(s):  
Contractile Activity ◽  
Myosin Ii ◽  
Focal Adhesions ◽  
Traction Force ◽  
Stress Fiber ◽  
Force Generation ◽  
Stress Fibers ◽  
Force Microscopy ◽  
Fiber Dynamics ◽  
The Relationship

REF52 fibroblasts have a well-developed contractile machinery, the most prominent elements of which are actomyosin stress fibers with highly ordered organization of actin and myosin IIA filaments. The relationship between contractile activity and turnover dynamics of stress fibers is not sufficiently understood. Here, we simultaneously measured the forces exerted by stress fibers (using traction force microscopy or micropillar array sensors) and the dynamics of actin and myosin (using photoconversion-based monitoring of actin incorporation and high-resolution fluorescence microscopy of myosin II light chain). Our data revealed new features of the crosstalk between myosin II-driven contractility and stress fiber dynamics. During normal stress fiber turnover, actin incorporated all along the stress fibers and not only at focal adhesions. Incorporation of actin into stress fibers/focal adhesions, as well as actin and myosin II filaments flow along stress fibers, strongly depends on myosin II activity. Myosin II-dependent generation of traction forces does not depend on incorporation of actin into stress fibers per se, but still requires formin activity. This previously overlooked function of formins in maintenance of the actin cytoskeleton connectivity could be the main mechanism of formin involvement in traction force generation.

scholarly journals Phagocytic 'teeth' and myosin-II 'jaw' power target constriction during phagocytosis

2021 ◽  
Author(s):  
Daan Vorselen ◽  
Sarah R. Barger ◽  
Yifan Wang ◽  
Wei Cai ◽  
Julie A. Theriot ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Traction Force ◽  
Light Sheet ◽  
Force Generation ◽  
Actin Dynamics ◽  
Force Microscopy ◽  
Light Sheet Microscopy ◽  
Macrophage Phagocytosis ◽  
Actin Protrusions

Phagocytosis requires rapid actin reorganization and spatially controlled force generation to ingest targets ranging from pathogens to apoptotic cells. How actomyosin activity directs membrane extensions to engulf such diverse targets remains unclear. Here, we combine lattice light-sheet microscopy (LLSM) with microparticle traction force microscopy (MP-TFM) to quantify actin dynamics and subcellular forces during macrophage phagocytosis. We show that spatially localized forces leading to target constriction are prominent during phagocytosis of antibody-opsonized targets. This constriction is largely mediated by Arp2/3-mediated assembly of discrete actin protrusions containing myosin 1e and 1f ('teeth') that are interconnected in a ring-like organization. Contractile myosin-II activity contributes to late-stage phagocytic force generation and progression, suggesting a specific role in phagocytic cup closure. Observations of partial target eating attempts and sudden target release via a popping mechanism suggest that constriction may be critical for resolving complex in vivo target encounters. Overall, our findings suggest a phagocytic cup-shaping mechanism that is distinct from cytoskeletal remodeling in 2D cell motility and may contribute to mechanosensing and phagocytic plasticity.

scholarly journals How Localized Z-Disc Damage Affects Force Generation and Gene Expression in Cardiomyocytes

2021 ◽  
Vol 8 (12) ◽  
pp. 213
Author(s):  
Dominik Müller ◽  
Sören Donath ◽  
Emanuel Georg Brückner ◽  
Santoshi Biswanath Devadas ◽  
Fiene Daniel ◽  
...  
Keyword(s):  
Gene Expression ◽  
Troponin I ◽  
Troponin T ◽  
Laser System ◽  
Traction Force ◽  
Force Generation ◽  
Proper Function ◽  
Force Microscopy ◽  
Vitro Model

The proper function of cardiomyocytes (CMs) is highly related to the Z-disc, which has a pivotal role in orchestrating the sarcomeric cytoskeletal function. To better understand Z-disc related cardiomyopathies, novel models of Z-disc damage have to be developed. Human pluripotent stem cell (hPSC)-derived CMs can serve as an in vitro model to better understand the sarcomeric cytoskeleton. A femtosecond laser system can be applied for localized and defined damage application within cells as single Z-discs can be removed. We have investigated the changes in force generation via traction force microscopy, and in gene expression after Z-disc manipulation in hPSC-derived CMs. We observed a significant weakening of force generation after removal of a Z-disc. However, no significant changes of the number of contractions after manipulation were detected. The stress related gene NF-kB was significantly upregulated. Additionally, α-actinin (ACTN2) and filamin-C (FLNc) were upregulated, pointing to remodeling of the Z-disc and the sarcomeric cytoskeleton. Ultimately, cardiac troponin I (TNNI3) and cardiac muscle troponin T (TNNT2) were significantly downregulated. Our results allow a better understanding of transcriptional coupling of Z-disc damage and the relation of damage to force generation and can therefore finally pave the way to novel therapies of sarcomeric disorders.

scholarly journals ATP allosterically stabilizes Integrin-linked kinase for efficient force generation

2021 ◽  
Author(s):  
Isabel M. Martin ◽  
Michele M. Nava ◽  
Sara A. Wickstroem ◽  
Frauke Graeter
Keyword(s):  
Focal Adhesion ◽  
Protein Unfolding ◽  
Focal Adhesions ◽  
Traction Force ◽  
Force Generation ◽  
Force Microscopy ◽  
Integrin Linked Kinase ◽  
And Migration ◽  
Dynamics Simulations ◽  
Propagation Network

Focal adhesions link the actomyosin cytoskeleton to the extracellular matrix regulating cell adhesion, shape, and migration. Adhesions are dynamically assembled and disassembled in response to extrinsic and intrinsic forces, but how the essential adhesion component intergrin-linked kinase (ILK) dynamically responds to mechanical force and what role ATP bound to this pseudokinase plays remains elusive. Here, we apply force-probe molecular dynamics simulations of ILK:alpha-parvin coupled to traction force microscopy to explore ILK mechanotransducing functions. We identify two key saltbridge-forming arginines within the allosteric, ATP-dependent force-propagation network of ILK. Disrupting this network by mutation impedes parvin binding, focal adhesion stabilization, force generation, and thus migration. Under tension, ATP shifts the balance from rupture of the complex to protein unfolding, indicating that ATP increases the force threshold required for focal adhesion disassembly. Our study proposes a new role of ATP as an obligatory binding partner for structural and mechanical integrity of the pseudokinase ILK, ensuring efficient cellular force generation and migration.

scholarly journals Dynamics of force generation by spreading platelets

Soft Matter ◽  
2018 ◽  
Vol 14 (31) ◽  
pp. 6571-6581 ◽  
Author(s):  
Jana Hanke ◽  
Dimitri Probst ◽  
Assaf Zemel ◽  
Ulrich S. Schwarz ◽  
Sarah Köster
Keyword(s):  
Internal Stress ◽  
Traction Force ◽  
Variable Stiffness ◽  
Human Platelets ◽  
Force Generation ◽  
Dynamic Force ◽  
Time Resolved ◽  
Force Microscopy ◽  
Elastic Substrates ◽  
High Level

Using time-resolved traction force microscopy on soft elastic substrates of variable stiffness, here we show that human platelets generate highly dynamic force patterns and an exceptionally high level of internal stress.

scholarly journals Direct measurement of the lamellipodial protrusive force in a migrating cell

2006 ◽  
Vol 174 (6) ◽  
pp. 767-772 ◽  
Author(s):  
Marcus Prass ◽  
Ken Jacobson ◽  
Alex Mogilner ◽  
Manfred Radmacher
Keyword(s):  
Actin Filaments ◽  
Actin Polymerization ◽  
Leading Edge ◽  
Theoretical Models ◽  
Force Generation ◽  
Direct Measure ◽  
Force Microscopy ◽  
Atomic Force ◽  
Force Velocity ◽  
Atomic Force Microscopy Cantilever

There has been a great deal of interest in the mechanism of lamellipodial protrusion (Pollard, T., and G. Borisy. 2003. Cell. 112:453–465). However, one of this mechanism's endpoints, the force of protrusion, has never been directly measured. We place an atomic force microscopy cantilever in the path of a migrating keratocyte. The deflection of the cantilever, which occurs over a period of ∼10 s, provides a direct measure of the force exerted by the lamellipodial leading edge. Stall forces are consistent with ∼100 polymerizing actin filaments per micrometer of the leading edge, each working as an elastic Brownian ratchet and generating a force of several piconewtons. However, the force-velocity curves obtained from this measurement, in which velocity drops sharply under very small loads, is not sensitive to low loading forces, and finally stalls rapidly at large loads, are not consistent with current theoretical models for the actin polymerization force. Rather, the curves indicate that the protrusive force generation is a complex multiphase process involving actin and adhesion dynamics.

Cryogenic atomic force microscopy

1991 ◽  
Vol 49 ◽  
pp. 54-55
Author(s):  
K. A. Fisher ◽  
M. G. L. Gustafsson ◽  
M. B. Shattuck ◽  
J. Clarke
Keyword(s):  
Room Temperature ◽  
Rapid Freezing ◽  
Cryogenic Temperatures ◽  
Soft Or ◽  
Electrically Conductive ◽  
Force Microscopy ◽  
Flexible Molecules ◽  
Advantages And Disadvantages ◽  
Atomic Force ◽  
Chemical Perturbation

The atomic force microscope (AFM) is capable of imaging electrically conductive and non-conductive surfaces at atomic resolution. When used to image biological samples, however, lateral resolution is often limited to nanometer levels, due primarily to AFM tip/sample interactions. Several approaches to immobilize and stabilize soft or flexible molecules for AFM have been examined, notably, tethering coating, and freezing. Although each approach has its advantages and disadvantages, rapid freezing techniques have the special advantage of avoiding chemical perturbation, and minimizing physical disruption of the sample. Scanning with an AFM at cryogenic temperatures has the potential to image frozen biomolecules at high resolution. We have constructed a force microscope capable of operating immersed in liquid n-pentane and have tested its performance at room temperature with carbon and metal-coated samples, and at 143° K with uncoated ferritin and purple membrane (PM).

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