Roles of Talin2 in Traction Force Generation, Tumor Metastasis and Cardiovascular Integrity

Vinculin transduces force and orchestrates mechanical signalling at cell–cell and cell–matrix adhesions. Cells expressing a mutant vinculin deficient in actin binding and bundling display migration and traction force defects. Vinculin binding to actin is critical for cell migration and force generation.

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

eLife ◽

10.7554/elife.68627 ◽

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.

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Subendothelial stiffness alters endothelial cell traction force generation while exerting a minimal effect on the transcriptome

Scientific Reports ◽

10.1038/s41598-019-54336-2 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Effie E. Bastounis ◽

Yi-Ting Yeh ◽

Julie A. Theriot

Keyword(s):

Endothelial Cells ◽

Endothelial Cell ◽

Conformational Changes ◽

Umbilical Vein ◽

Traction Force ◽

Cell Types ◽

Force Generation ◽

Dependent Manner ◽

Cell Transcriptome ◽

Umbilical Vein Endothelial Cells

AbstractEndothelial cells respond to changes in subendothelial stiffness by altering their migration and mechanics, but whether those responses are due to transcriptional reprogramming remains largely unknown. We measured traction force generation and also performed gene expression profiling for two endothelial cell types grown in monolayers on soft or stiff matrices: primary human umbilical vein endothelial cells (HUVEC) and immortalized human microvascular endothelial cells (HMEC-1). Both cell types respond to changes in subendothelial stiffness by increasing the traction stresses they exert on stiffer as compared to softer matrices, and exhibit a range of altered protein phosphorylation or protein conformational changes previously implicated in mechanotransduction. However, the transcriptome has only a minimal role in this conserved biomechanical response. Only few genes were differentially expressed in each cell type in a stiffness-dependent manner, and none were shared between them. In contrast, thousands of genes were differentially regulated in HUVEC as compared to HMEC-1. HUVEC (but not HMEC-1) upregulate expression of TGF-β2 on stiffer matrices, and also respond to application of exogenous TGF-β2 by enhancing their endogenous TGF-β2 expression and their cell-matrix traction stresses. Altogether, these findings provide insights into the relationship between subendothelial stiffness, endothelial mechanics and variation of the endothelial cell transcriptome, and reveal that subendothelial stiffness, while critically altering endothelial cells’ mechanical behavior, minimally affects their transcriptome.

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A β2-Integrin/MRTF-A/SRF Pathway Regulates Dendritic Cell Gene Expression, Adhesion, and Traction Force Generation

Frontiers in Immunology ◽

10.3389/fimmu.2019.01138 ◽

2019 ◽

Vol 10 ◽

Cited By ~ 1

Author(s):

Carla Guenther ◽

Imrul Faisal ◽

Liisa M. Uotila ◽

Marc Llort Asens ◽

Heidi Harjunpää ◽

...

Keyword(s):

Gene Expression ◽

Dendritic Cell ◽

Traction Force ◽

Force Generation ◽

Β2 Integrin ◽

Cell Gene Expression ◽

Cell Gene

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Regulation of SMC traction forces in human aortic thoracic aneurysms

Biomechanics and Modeling in Mechanobiology ◽

10.1007/s10237-020-01412-6 ◽

2021 ◽

Author(s):

Claudie Petit ◽

Ali-Akbar Karkhaneh Yousefi ◽

Olfa Ben Moussa ◽

Jean-Baptiste Michel ◽

Alain Guignandon ◽

...

Keyword(s):

Traction Force ◽

Aortic Aneurysms ◽

Force Generation ◽

Dynamic Force ◽

Generation Process ◽

Traction Forces ◽

Thoracic Aortic Aneurysms ◽

And Gender ◽

Thoracic Aneurysms ◽

Future Work

AbstractSmooth muscle cells (SMCs) usually express a contractile phenotype in the healthy aorta. However, aortic SMCs have the ability to undergo profound changes in phenotype in response to changes in their extracellular environment, as occurs in ascending thoracic aortic aneurysms (ATAA). Accordingly, there is a pressing need to quantify the mechanobiological effects of these changes at single cell level. To address this need, we applied Traction Force Microscopy (TFM) on 759 cells coming from three primary healthy (AoPrim) human SMC lineages and three primary aneurysmal (AnevPrim) human SMC lineages, from age and gender matched donors. We measured the basal traction forces applied by each of these cells onto compliant hydrogels of different stiffness (4, 8, 12, 25 kPa). Although the range of force generation by SMCs suggested some heterogeneity, we observed that: 1. the traction forces were significantly larger on substrates of larger stiffness; 2. traction forces in AnevPrim were significantly higher than in AoPrim cells. We modelled computationally the dynamic force generation process in SMCs using the motor-clutch model and found that it accounts well for the stiffness-dependent traction forces. The existence of larger traction forces in the AnevPrim SMCs were related to the larger size of cells in these lineages. We conclude that phenotype changes occurring in ATAA, which were previously known to reduce the expression of elongated and contractile SMCs (rendering SMCs less responsive to vasoactive agents), tend also to induce stronger SMCs. Future work aims at understanding the causes of this alteration process in aortic aneurysms.

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

10.1101/2021.08.15.456175 ◽

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.

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