scholarly journals Dexamethasone induces gelsolin synthesis and altered morphology in L929 cells

1983 ◽  
Vol 96 (2) ◽  
pp. 577-581 ◽  
Author(s):  
KW Lanks ◽  
EJ Kasambalides
Keyword(s):  
Cell Shape ◽  
Actin Polymerization ◽  
Two Dimensional ◽  
L929 Cells

When L929 cells are exposed to 5 μg/ml dexamethasone, synthesis of a 90,000 M(r) polypeptide is induced within 12 h. Flattening of the cells begins at about this time and progresses to become quite prominent after 48 h of exposure. Two-dimensional PAGE and partial proteolytic fingerprints identify the 90,000 M(r) polypeptide as gelsolin, a Ca(++)-dependent inhibitor of actin polymerization. Thus, this system provides evidence that gelsolin may have a role in regulating cell shape in response to physiological agents such as glucocorticoids.

Author response for "Tweedle proteins form extracellular two-dimensional structures defining body and cell shape in Drosophila melanogaster"

2020 ◽  
Author(s):  
Renata Zuber ◽  
Yiwen Wang ◽  
Nicole Gehring ◽  
Slawomir Bartoszewski ◽  
Bernard Moussian
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Shape ◽  
Author Response ◽  
Two Dimensional

scholarly journals Dia1 and IQGAP1 interact in cell migration and phagocytic cup formation

2007 ◽  
Vol 178 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Dominique T. Brandt ◽  
Sabrina Marion ◽  
Gareth Griffiths ◽  
Takashi Watanabe ◽  
Kozo Kaibuchi ◽  
...  
Keyword(s):  
Cell Migration ◽  
Actin Filament ◽  
Cell Shape ◽  
Actin Polymerization ◽  
Binding Protein ◽  
Subcellular Location ◽  
Scaffold Protein ◽  
Cellular Location ◽  
Inhibitory Domain ◽  
Migrating Cells

The Diaphanous-related formin Dia1 nucleates actin polymerization, thereby regulating cell shape and motility. Mechanisms that control the cellular location of Dia1 to spatially define actin polymerization are largely unknown. In this study, we identify the cytoskeletal scaffold protein IQGAP1 as a Dia1-binding protein that is necessary for its subcellular location. IQGAP1 interacts with Dia1 through a region within the Diaphanous inhibitory domain after the RhoA-mediated release of Dia1 autoinhibition. Both proteins colocalize at the front of migrating cells but also at the actin-rich phagocytic cup in macrophages. We show that IQGAP1 interaction with Dia1 is required for phagocytosis and phagocytic cup formation. Thus, we identify IQGAP1 as a novel component involved in the regulation of phagocytosis by mediating the localization of the actin filament nucleator Dia1.

TWO-DIMENSIONAL VERTEX MODEL WITH LOCAL FRICTION COEFFICIENT

1989 ◽  
Vol 03 (01) ◽  
pp. 163-169 ◽  
Author(s):  
YOSHIHISA ENOMOTO ◽  
KYOZI KAWASAKI ◽  
TATSUZO NAGAI
Keyword(s):  
Cell Shape ◽  
The Other ◽  
Cellular Structures ◽  
Two Dimensional ◽  
Vertex Model ◽  
Topological Properties ◽  
Asymptotic Growth ◽  
Shape Distribution ◽  
Long Time ◽  
Time Periods

Time evolution of two-dimensional cellular structures is studied in the context of a deterministic vertex model. Simulating this model for long time periods we discuss two typical aspects of cellular structures. One is the asymptotic growth law of cell size and the other is concerned with the topological properties such as the cell shape distribution.

scholarly journals Actin polymerization or myosin contraction: two ways to build up cortical tension for symmetry breaking

2013 ◽  
Vol 368 (1629) ◽  
pp. 20130005 ◽  
Author(s):  
Kevin Carvalho ◽  
Joël Lemière ◽  
Fahima Faqir ◽  
John Manzi ◽  
Laurent Blanchoin ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Self Assembly ◽  
Actin Filaments ◽  
Cell Shape ◽  
Actin Polymerization ◽  
Cell Polarization ◽  
Critical Tension ◽  
Cell Shape Changes ◽  
Myosin Motors ◽  
Shape Changes

Cells use complex biochemical pathways to drive shape changes for polarization and movement. One of these pathways is the self-assembly of actin filaments and myosin motors that together produce the forces and tensions that drive cell shape changes. Whereas the role of actin and myosin motors in cell polarization is clear, the exact mechanism of how the cortex, a thin shell of actin that is underneath the plasma membrane, can drive cell shape changes is still an open question. Here, we address this issue using biomimetic systems: the actin cortex is reconstituted on liposome membranes, in an ‘outside geometry’. The actin shell is either grown from an activator of actin polymerization immobilized at the membrane by a biotin–streptavidin link, or built by simple adsorption of biotinylated actin filaments to the membrane, in the presence or absence of myosin motors. We show that tension in the actin network can be induced either by active actin polymerization on the membrane via the Arp2/3 complex or by myosin II filament pulling activity. Symmetry breaking and spontaneous polarization occur above a critical tension that opens up a crack in the actin shell. We show that this critical tension is reached by growing branched networks, nucleated by the Arp2/3 complex, in a concentration window of capping protein that limits actin filament growth and by a sufficient number of motors that pull on actin filaments. Our study provides the groundwork to understanding the physical mechanisms at work during polarization prior to cell shape modifications.

scholarly journals The kinetics of chemotactic peptide-induced change in F-actin content, F-actin distribution, and the shape of neutrophils.

1985 ◽  
Vol 101 (3) ◽  
pp. 1078-1085 ◽  
Author(s):  
T H Howard ◽  
C O Oresajo
Keyword(s):  
Cell Shape ◽  
Actin Polymerization ◽  
Time Course ◽  
Control Level ◽  
Actin Depolymerization ◽  
Cell Biol ◽  
Rate Of Polymerization ◽  
Resultant Increase ◽  
Cellular Locomotion ◽  
Cell Changes

Formyl-met-leu-phe (fMLP) induces actin assembly in neutrophils; the resultant increase in F-actin content correlates with an increase in the rate of cellular locomotion at fMLP concentrations less than or equal to 10(-8) M (Howard, T.H., and W.H. Meyer, 1984, J. Cell Biol., 98:1265-1271). We studied the time course of change in F-actin content, F-actin distribution, and cell shape after fMLP stimulation. F-actin content was quantified by fluorescence activated cell sorter analysis of nitrobenzoxadiazole-phallacidin-stained cells (Howard, T.H., 1982, J. Cell Biol., 95(2, Pt. 2:327a). F-actin distribution and cell shape were determined by analysis of fluorescence photomicrographs of nitrobenzoxadiazole-phallacidin-stained cells. After fMLP stimulation at 25 degrees C, there is a rapid actin polymerization that is maximal (up to 2.0 times the control level) at 45 s; subsequently, the F-actin depolymerizes to an intermediate F-actin content 5-10 min after stimulation. The depolymerization of F-actin reflects a true decrease in F-actin content since the quantity of probe extractable from cells also decreases between 45 s and 10 min. The rate of actin polymerization (3.8 +/- 0.3-4.4 +/- 0.6% increase in F-actin/s) is the same for 10(-10) - 10(-6) M fMLP and the polymerization is inhibited by cytochalasin D. The initial rate of F-actin depolymerization (6.0 +/- 1.0-30 +/- 5% decrease in F-actin/min) is inversely proportional to fMLP dose. The F-actin content of stimulated cells at 45 s and 10 min is greater than control levels and varies directly with fMLP dose. F-actin distribution and cell shape also vary as a function of time after stimulation. 45 s after stimulation the cells are rounded and F-actin is diffusely distributed; 10 min after stimulation the cell is polarized and F-actin is focally distributed. These results indicate that actin polymerization and depolymerization follow fMLP stimulation in sequence, the rate of depolymerization and the maximum and steady state F-actin content but not the rate of polymerization are fMLP dose dependent, and concurrent with F-actin depolymerization, F-actin is redistributed and the cell changes shape.

scholarly journals Membrane-cytoskeleton mechanical feedback mediated by myosin-I controls phagocytic efficiency

2018 ◽  
Author(s):  
Sarah R. Barger ◽  
Nicholas S. Reilly ◽  
Maria S. Shutova ◽  
Qingsen Li ◽  
Paolo Maiuri ◽  
...  
Keyword(s):  
Molecular Motors ◽  
Cell Shape ◽  
Actin Polymerization ◽  
Target Surface ◽  
Feedback Mechanism ◽  
Membrane Tension ◽  
Membrane Cytoskeleton ◽  
Myosin I ◽  
Cellular Debris ◽  
Class 1

AbstractPhagocytosis of invading pathogens or cellular debris requires a dramatic change in cell shape driven by actin polymerization. For antibody-covered targets, phagocytosis is thought to proceed through the sequential engagement of Fc-receptors on the phagocyte with antibodies on the target surface, leading to the extension and closure of the phagocytic cup around the target. We have found that two actin-dependent molecular motors, class 1 myosins myosin 1e and myosin 1f, are specifically localized to Fc-receptor adhesions and required for efficient phagocytosis of antibody-opsonized targets. Using primary macrophages lacking both myosin 1e and myosin 1f, we found that without the actin-membrane linkage mediated by these myosins, the organization of individual adhesions is compromised, leading to excessive actin polymerization, slower adhesion turnover, and deficient phagocytic internalization. This work identifies a novel role for class 1 myosins in coordinated adhesion turnover during phagocytosis and supports a model for a membrane-tension based feedback mechanism for phagocytic cup closure.

scholarly journals Mechanisms of cell shape change: the cytomechanics of cellular response to chemical environment and mechanical loading

1992 ◽  
Vol 117 (1) ◽  
pp. 83-93 ◽  
Author(s):  
DS Adams
Keyword(s):  
Mechanical Loading ◽  
Cell Shape ◽  
Cellular Response ◽  
Actin Polymerization ◽  
Shape Change ◽  
Theoretical Models ◽  
Mechanical Responses ◽  
Cell Shape Change ◽  
Length Changes ◽  
Cytoskeletal Elements

Processes such as cell locomotion and morphogenesis depend on both the generation of force by cytoskeletal elements and the response of the cell to the resulting mechanical loads. Many widely accepted theoretical models of processes involving cell shape change are based on untested hypotheses about the interaction of these two components of cell shape change. I have quantified the mechanical responses of cytoplasm to various chemical environments and mechanical loading regimes to understand better the mechanisms of cell shape change and to address the validity of these models. Measurements of cell mechanical properties were made with strands of cytoplasm submerged in media containing detergent to permeabilize the plasma membrane, thus allowing control over intracellular milieu. Experiments were performed with equipment that generated sinusoidally varying length changes of isolated strands of cytoplasm from Physarum polycephalum. Results indicate that stiffness, elasticity, and viscosity of cytoplasm all increase with increasing concentration of Ca2+, Mg2+, and ATP, and decrease with increasing magnitude and rate of deformation. These results specifically challenge assumptions underlying mathematical models of morphogenetic events such as epithelial folding and cell division, and further suggest that gelation may depend on both actin cross-linking and actin polymerization.

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