MYOSIN II REDISTRIBUTION DURING REAR RETRACTION AND THE ROLE OF FILAMENT ASSEMBLY AND DISASSEMBLY

2002 ◽  
Vol 26 (3) ◽  
pp. 287-296 ◽  
Author(s):  
G Koehl
Keyword(s):  
Myosin Ii ◽  
Filament Assembly

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.

scholarly journals The distribution of myosin II in Dictyostelium discoideum slug cells.

1991 ◽  
Vol 115 (5) ◽  
pp. 1267-1274 ◽  
Author(s):  
S Eliott ◽  
P H Vardy ◽  
K L Williams
Keyword(s):  
Cell Motility ◽  
Dictyostelium Discoideum ◽  
Immunofluorescence Microscopy ◽  
Molecular Genetic ◽  
Myosin Ii ◽  
Three Dimensional ◽  
Homogeneous Distribution ◽  
Multicellular Development ◽  
Insight Into

While the role of myosin II in muscle contraction has been well characterized, less is known about the role of myosin II in non-muscle cells. Recent molecular genetic experiments on Dictyostelium discoideum show that myosin II is necessary for cytokinesis and multicellular development. Here we use immunofluorescence microscopy with monoclonal and polyclonal antimyosin antibodies to visualize myosin II in cells of the multicellular D. discoideum slug. A subpopulation of peripheral and anterior cells label brightly with antimyosin II antibodies, and many of these cells display a polarized intracellular distribution of myosin II. Other cells in the slug label less brightly and their cytoplasm displays a more homogeneous distribution of myosin II. These results provide insight into cell motility within a three-dimensional tissue and they are discussed in relation to the possible roles of myosin II in multicellular development.

scholarly journals Myosin-II activity generates a dynamic steady state with continuous actin turnover in a minimal actin cortex

2018 ◽  
Author(s):  
Sonal ◽  
Kristina A. Ganzinger ◽  
Sven K. Vogel ◽  
Jonas Mücksch ◽  
Philipp Blumhardt ◽  
...  
Keyword(s):  
Steady State ◽  
Actin Polymerization ◽  
Myosin Ii ◽  
Fine Tuning ◽  
Cellular Functions ◽  
Actin Cortex ◽  
Actin Turnover ◽  
Cytoskeletal Dynamics

ABSTRACTDynamic reorganization of the actomyosin cytoskeleton allows a fine-tuning of cell shape that is vital to many cellular functions. It is well established that myosin-II motors generate the forces required for remodeling the cell surface by imparting contractility to actin networks. An additional, less understood, role of myosin-II in cytoskeletal dynamics is believed to be in the regulation of actin turnover; it has been proposed that myosin activity increases actin turnover in various cellular contexts, presumably by contributing to disassembly. In vitro reconstitution of actomyosin networks has confirmed the role of myosin in actin network disassembly, but factors such as diffusional constraints and the use of stabilized filaments have thus far limited the observation of myosin-assisted actin turnover in these networks. Here, we present the reconstitution of a minimal dynamic actin cortex where actin polymerization is catalyzed on the membrane in the presence of myosin-II activity. We demonstrate that myosin activity leads to disassembly and redistribution in this simplified cortex. Consequently, a new dynamic steady state emerges in which actin filaments undergo constant turnover. Our findings suggest a multi-faceted role of myosin-II in fast remodeling of the eukaryotic actin cortex.

scholarly journals Multiple Roles of Flagellar Export Chaperones for Efficient and Robust Flagellar Filament Formation in Salmonella

2021 ◽  
Vol 12 ◽  
Author(s):  
Tohru Minamino ◽  
Yusuke V. Morimoto ◽  
Miki Kinoshita ◽  
Keiichi Namba
Keyword(s):  
Type Iii Secretion ◽  
Culture Media ◽  
Multiple Roles ◽  
Filament Formation ◽  
Dynamic Interactions ◽  
Filament Assembly ◽  
Suppressor Mutations ◽  
Folded Structure ◽  
Flagellar Filament

FlgN, FliS, and FliT are flagellar export chaperones specific for FlgK/FlgL, FliC, and FliD, respectively, which are essential component proteins for filament formation. These chaperones facilitate the docking of their cognate substrates to a transmembrane export gate protein, FlhA, to facilitate their subsequent unfolding and export by the flagellar type III secretion system (fT3SS). Dynamic interactions of the chaperones with FlhA are thought to determine the substrate export order. To clarify the role of flagellar chaperones in filament assembly, we constructed cells lacking FlgN, FliS, and/or FliT. Removal of either FlgN, FliS, or FliT resulted in leakage of a large amount of unassembled FliC monomers into the culture media, indicating that these chaperones contribute to robust and efficient filament formation. The ∆flgN ∆fliS ∆fliT (∆NST) cells produced short filaments similarly to the ∆fliS mutant. Suppressor mutations of the ∆NST cells, which lengthened the filament, were all found in FliC and destabilized the folded structure of FliC monomer. Deletion of FliS inhibited FliC export and filament elongation only after FliC synthesis was complete. We propose that FliS is not involved in the transport of FliC upon onset of filament formation, but FliS-assisted unfolding of FliC by the fT3SS becomes essential for its rapid and efficient export to form a long filament when FliC becomes fully expressed in the cytoplasm.

scholarly journals Emerging Role of Nonmuscle Myosin II and Implications for NMMII Associated Deafness

2011 ◽  
Vol 145 (2_suppl) ◽  
pp. P209-P210
Author(s):  
Elliott Kozin ◽  
Bechara Kachar ◽  
Felipe Salles ◽  
Robert Adelstein ◽  
Xuefei Ma ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Nonmuscle Myosin ◽  
Nonmuscle Myosin Ii

Role of myosin II tail sequences in its function and localization at the cleavage furrow in Dictyostelium

1999 ◽  
Vol 112 (13) ◽  
pp. 2195-2201 ◽  
Author(s):  
S. Shu ◽  
R.J. Lee ◽  
J.M. LeBlanc-Straceski ◽  
T.Q. Uyeda
Keyword(s):  
Myosin Head ◽  
Myosin Ii ◽  
Equatorial Region ◽  
Chain Gene ◽  
Cleavage Furrow ◽  
Tail Domain ◽  
Specific Domain ◽  
Dictyostelium Myosin ◽  
Skeletal Myosin

Cytoplasmic myosin II accumulates in the cleavage furrow and provides the force for cytokinesis in animal and amoeboid cells. One model proposes that a specific domain in the myosin II tail is responsible for its localization, possibly by interacting with a factor concentrated in the equatorial region. To test this possibility, we have expressed myosins carrying mutations in the tail domain in a strain of Dictyostelium cells from which the endogenous myosin heavy chain gene has been deleted. The mutations used in this study include four internal tail deletions: Mydelta824-941, Mydelta943-1464, Mydelta943-1194 and Mydelta1156-1464. Contrary to the prediction of the hypothesis, immunofluorescence staining demonstrated that all mutant myosins were able to move toward the furrow region. Chimeric myosins, which consisted of a Dictyostelium myosin head and chicken skeletal myosin tail, also efficiently localized to the cleavage furrow. All these deletion and chimeric mutant myosins, except for Mydelta943-1464, the largest deletion mutant, were able to support cytokinesis in suspension. Our data suggest that there is no single specific domain in the tail of Dictyostelium myosin II that is required for its functioning at and localization to the cleavage furrow.

scholarly journals Anchoring of actin to the plasma membrane enables tension production in the fission yeast cytokinetic ring

2019 ◽  
Vol 30 (16) ◽  
pp. 2053-2064 ◽  
Author(s):  
Shuyuan Wang ◽  
Ben O’Shaughnessy
Keyword(s):  
Plasma Membrane ◽  
Fission Yeast ◽  
Actin Filaments ◽  
Tensile Force ◽  
Myosin Ii ◽  
Quantitative Evidence ◽  
Explicit Simulation ◽  
Adjacent Segments ◽  
Develop Tension

The cytokinetic ring generates tensile force that drives cell division, but how tension emerges from the relatively disordered ring organization remains unclear. Long ago, a musclelike sliding filament mechanism was proposed, but evidence for sarcomeric order is lacking. Here we present quantitative evidence that in fission yeast, ring tension originates from barbed-end anchoring of actin filaments to the plasma membrane, providing resistance to myosin forces that enables filaments to develop tension. The role of anchoring was highlighted by experiments on isolated fission yeast rings, where sections of ring became unanchored from the membrane and shortened ∼30-fold faster than normal. The dramatically elevated constriction rates are unexplained. Here we present a molecularly explicit simulation of constricting partially anchored rings as studied in these experiments. Simulations accurately reproduced the experimental constriction rates and showed that following anchor release, a segment becomes tensionless and shortens via a novel noncontractile reeling-in mechanism at about the velocity of load-free myosin II. The ends are reeled in by barbed end–anchored actin filaments in adjacent segments. Other actin anchoring schemes failed to constrict rings. Our results quantitatively support a specific organization and anchoring scheme that generate tension in the cytokinetic ring.

scholarly journals Tension is required but not sufficient for focal adhesion maturation without a stress fiber template

2012 ◽  
Vol 196 (3) ◽  
pp. 363-374 ◽  
Author(s):  
Patrick W. Oakes ◽  
Yvonne Beckham ◽  
Jonathan Stricker ◽  
Margaret L. Gardel
Keyword(s):  
Focal Adhesion ◽  
Myosin Ii ◽  
Focal Adhesions ◽  
Stress Fiber ◽  
Matrix Remodeling ◽  
Force Transmission ◽  
Fiber Assembly ◽  
Wide Range ◽  
Structural Template

Focal adhesion composition and size are modulated in a myosin II–dependent maturation process that controls adhesion, migration, and matrix remodeling. As myosin II activity drives stress fiber assembly and enhanced tension at adhesions simultaneously, the extent to which adhesion maturation is driven by tension or altered actin architecture is unknown. We show that perturbations to formin and α-actinin 1 activity selectively inhibited stress fiber assembly at adhesions but retained a contractile lamella that generated large tension on adhesions. Despite relatively unperturbed adhesion dynamics and force transmission, impaired stress fiber assembly impeded focal adhesion compositional maturation and fibronectin remodeling. Finally, we show that compositional maturation of focal adhesions could occur even when myosin II–dependent cellular tension was reduced by 80%. We propose that stress fiber assembly at the adhesion site serves as a structural template that facilitates adhesion maturation over a wide range of tensions. This work identifies the essential role of lamellar actin architecture in adhesion maturation.

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