scholarly journals Myosin-II Mediated Traction Forces Evoke Localized Piezo1 Ca2+ Flickers

2019 ◽  
Vol 116 (3) ◽  
pp. 377a ◽  
Author(s):  
Kyle L. Ellefsen ◽  
Alice Chang ◽  
Jamison L. Nourse ◽  
Jesse R. Holt ◽  
Janahan Arulmoli ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Traction Forces

scholarly journals Myosin II Is Essential for the Spatiotemporal Organization of Traction Forces during Cell Motility

2010 ◽  
Vol 21 (3) ◽  
pp. 405-417 ◽  
Author(s):  
Ruedi Meili ◽  
Baldomero Alonso-Latorre ◽  
Juan C. del Álamo ◽  
Richard A. Firtel ◽  
Juan C. Lasheras
Keyword(s):  
Actin Polymerization ◽  
Myosin Ii ◽  
Cross Linking ◽  
Traction Forces ◽  
Amoeboid Motility ◽  
Periodic Repetition ◽  
Time Required ◽  
Tensional Stress ◽  
Motility Cycle ◽  
Analytical Tools

Amoeboid motility requires spatiotemporal coordination of biochemical pathways regulating force generation and consists of the quasi-periodic repetition of a motility cycle driven by actin polymerization and actomyosin contraction. Using new analytical tools and statistical methods, we provide, for the first time, a statistically significant quantification of the spatial distribution of the traction forces generated at each phase of the cycle (protrusion, contraction, retraction, and relaxation). We show that cells are constantly under tensional stress and that wild-type cells develop two opposing “pole” forces pulling the front and back toward the center whose strength is modulated up and down periodically in each cycle. We demonstrate that nonmuscular myosin II complex (MyoII) cross-linking and motor functions have different roles in controlling the spatiotemporal distribution of traction forces, the changes in cell shape, and the duration of all the phases. We show that the time required to complete each phase is dramatically increased in cells with altered MyoII motor function, demonstrating that it is required not only for contraction but also for protrusion. Concomitant loss of MyoII actin cross-linking leads to a force redistribution throughout the cell perimeter pulling inward toward the center. However, it does not reduce significantly the magnitude of the traction forces, uncovering a non–MyoII-mediated mechanism for the contractility of the cell.

scholarly journals Myosin-II mediated traction forces evoke localized Piezo1-dependent Ca2+ flickers

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Kyle L. Ellefsen ◽  
Jesse R. Holt ◽  
Alice C. Chang ◽  
Jamison L. Nourse ◽  
Janahan Arulmoli ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Traction Forces

scholarly journals Nonmuscle Myosin IIB Is Involved in the Guidance of Fibroblast Migration

2004 ◽  
Vol 15 (3) ◽  
pp. 982-989 ◽  
Author(s):  
Chun-Min Lo ◽  
Denis B. Buxton ◽  
Gregory C.H. Chua ◽  
Micah Dembo ◽  
Robert S. Adelstein ◽  
...  
Keyword(s):  
Cell Migration ◽  
Large Fraction ◽  
Myosin Ii ◽  
Cell Movement ◽  
Traction Forces ◽  
Migration Patterns ◽  
Fibroblast Migration ◽  
Substrate Rigidity ◽  
Migration Analysis ◽  
Mutant Cells

Although myosin II is known to play an important role in cell migration, little is known about its specific functions. We have addressed the function of one of the isoforms of myosin II, myosin IIB, by analyzing the movement and mechanical characteristics of fibroblasts where this protein has been ablated by gene disruption. Myosin IIB null cells displayed multiple unstable and disorganized protrusions, although they were still able to generate a large fraction of traction forces when cultured on flexible polyacrylamide substrates. However, the traction forces were highly disorganized relative to the direction of cell migration. Analysis of cell migration patterns indicated an increase in speed and decrease in persistence, which were likely responsible for the defects in directional movements as demonstrated with Boyden chambers. In addition, unlike control cells, mutant cells failed to respond to mechanical signals such as compressing forces and changes in substrate rigidity. Immunofluorescence staining indicated that myosin IIB was localized preferentially along stress fibers in the interior region of the cell. Our results suggest that myosin IIB is involved not in propelling but in directing the cell movement, by coordinating protrusive activities and stabilizing the cell polarity.

scholarly journals Myosin-II mediated traction forces evoke localized Piezo1 Ca2+ flickers

2018 ◽  
Author(s):  
Kyle L. Ellefsen ◽  
Jesse R. Holt ◽  
Alice Chang ◽  
Jamison L. Nourse ◽  
Janahan Arulmoli ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Myosin Ii ◽  
Tissue Homeostasis ◽  
Mechanical Forces ◽  
Mechanical Stimuli ◽  
Traction Forces ◽  
Internal Cell ◽  
External Forces

ABSTRACTPiezo channels transduce mechanical stimuli into electrical and chemical signals, and in doing so, powerfully influence development, tissue homeostasis, and regeneration. While much is known about how Piezo1 responds to external forces, its response to internal, cell-generated forces remains poorly understood. Here, using measurements of endogenous Piezo1 activity and traction forces in native cellular conditions, we show that actomyosin-based cellular traction forces generate spatially-restricted Ca2+ flickers in the absence of externally-applied mechanical forces. Although Piezo1 channels diffuse readily in the plasma membrane and are widely distributed across the cell, their flicker activity is enriched in regions proximal to force-producing adhesions. The mechanical force that activates Piezo1 arises from Myosin II phosphorylation by Myosin Light Chain Kinase. We propose that Piezo1 Ca2+ flickers allow spatial segregation of mechanotransduction events, and that diffusion allows channel molecules to efficiently respond to transient, local mechanical stimuli.

Video-microscopic measurement of cell-substratum traction forces generated by locomoting keratocytes

1993 ◽  
Vol 51 ◽  
pp. 188-189
Author(s):  
Tim Oliver ◽  
Michelle Leonard ◽  
Juliet Lee ◽  
Akira Ishihara ◽  
Ken Jacobson
Keyword(s):  
Silicone Rubber ◽  
Molecular Motors ◽  
Video Frame ◽  
Traction Forces ◽  
Cell Traction Forces ◽  
Latex Beads ◽  
Cell Traction ◽  
Local Cell ◽  
Microscopic Measurement ◽  
Kinetics Of

We are using video-enhanced light microscopy to investigate the pattern and magnitude of forces that fish keratocytes exert on flexible silicone rubber substrata. Our goal is a clearer understanding of the way molecular motors acting through the cytoskeleton co-ordinate their efforts into locomotion at cell velocities up to 1 μm/sec. Cell traction forces were previously observed as wrinkles(Fig.l) in strong silicone rubber films by Harris.(l) These forces are now measureable by two independant means.In the first of these assays, weakly crosslinked films are made, into which latex beads have been embedded.(Fig.2) These films report local cell-mediated traction forces as bead displacements in the plane of the film(Fig.3), which recover when the applied force is released. Calibrated flexible glass microneedles are then used to reproduce the translation of individual beads. We estimate the force required to distort these films to be 0.5 mdyne/μm of bead movement. Video-frame analysis of bead trajectories is providing data on the relative localisation, dissipation and kinetics of traction forces.

Magnesium Chloride is an Effective Therapeutic Agent for Prostate Cancer

2018 ◽  
Vol 8 (1) ◽  
pp. 62 ◽  
Author(s):  
Julianna Maria Santos ◽  
Fazle Hussain
Keyword(s):  
Prostate Cancer ◽  
Magnesium Chloride ◽  
Epithelial Mesenchymal Transition ◽  
Chromatin Condensation ◽  
Myosin Ii ◽  
In Vivo Studies ◽  
Migration Speed ◽  
Mesenchymal Transition

Background: Reduced levels of magnesium can cause several diseases and increase cancer risk. Motivated by magnesium chloride’s (MgCl2) non-toxicity, physiological importance, and beneficial clinical applications, we studied its action mechanism and possible mechanical, molecular, and physiological effects in prostate cancer with different metastatic potentials.Methods: We examined the effects of MgCl2, after 24 and 48 hours, on apoptosis, cell migration, expression of epithelial mesenchymal transition (EMT) markers, and V-H+-ATPase, myosin II (NMII) and the transcription factor NF Kappa B (NFkB) expressions.Results: MgCl2 induces apoptosis, and significantly decreases migration speed in cancer cells with different metastatic potentials.  MgCl2 reduces the expression of V-H+-ATPase and myosin II that facilitates invasion and metastasis, suppresses the expression of vimentin and increases expression of E-cadherin, suggesting a role of MgCl2 in reversing the EMT. MgCl2 also significantly increases the chromatin condensation and decreases NFkB expression.Conclusions: These results suggest a promising preventive and therapeutic role of MgCl2 for prostate cancer. Further studies should explore extending MgCl2 therapy to in vivo studies and other cancer types.Keywords: Magnesium chloride, prostate cancer, migration speed, V-H+-ATPase, and EMT.

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