Faculty Opinions recommendation of Direct comparisons of the morphology, migration, cell adhesions, and actin cytoskeleton of fibroblasts in four different three-dimensional extracellular matrices.

Author(s):  
Alan Rick Horwitz
2012 ◽  
Vol 195 (1-2) ◽  
pp. 122-143 ◽  
Author(s):  
Anastasia Sacharidou ◽  
Amber N. Stratman ◽  
George E. Davis

Author(s):  
Pavel Vesely ◽  
Luboslava Pavlikova ◽  
Jiri Plachy ◽  
Katerina Trejbalova ◽  
Jiri Hejnar ◽  
...  

2003 ◽  
Vol 14 (12) ◽  
pp. 4871-4884 ◽  
Author(s):  
Bo Huang ◽  
Guisheng Zeng ◽  
Alvin Y.J. Ng ◽  
Mingjie Cai

Prk1p is a serine/threonine kinase involved in the regulation of the actin cytoskeleton organization in the yeast Saccharomyces cerevisiae. Previously, we have identified LxxQxTG as the phosphorylation site of Prk1p. In this report, the recognition sequence for Prk1p is investigated more thoroughly. It is found that the presence of a hydrophobic residue at the position of P-5 is necessary for Prk1p phosphorylation and L, I, V, and M are all able to confer the phosphorylation at various efficiencies. The residue flexibility at P-2 has also been identified to include Q, N, T, and S. A homology-based three-dimensional model of the kinase domain of Prk1p provided some structural interpretations for these substrate specificities. The characterization of the [L/I/V/M]xx[Q/N/T/S]xTG motif led to the identification of a spectrum of potential targets for Prk1p from yeast genome. One of them, Scd5p, which contains three LxxTxTG motifs and is previously known to be important for endocytosis and actin organization, has been chosen to demonstrate its relationship with Prk1p. Phosphorylation of Scd5p by Prk1p at the three LxxTxTG motifs could be detected in vitro and in vivo, and deletion of PRK1 suppressed the defects in actin cytoskeleton and endocytosis in one of the scd5 mutants. These results allowed us to conclude that Scd5p is likely another regulatory target of Prk1p.


2008 ◽  
Vol 13 (2) ◽  
pp. A28-A48
Author(s):  
N.R. Washburn ◽  
M.D. Weir ◽  
K.M. Yamada

1995 ◽  
Vol 129 (6) ◽  
pp. 1575-1588 ◽  
Author(s):  
V Mermall ◽  
K G Miller

The 95F myosin, a class VI unconventional myosin, associates with particles in the cytoplasm of the Drosophila syncytial blastoderm and is required for the ATP- and F-actin-dependent translocation of these particles. The particles undergo a cell cycle-dependent redistribution from domains that surround each nucleus in interphase to transient membrane invaginations that provide a barrier between adjacent spindles during mitosis. When 95F myosin function is inhibited by antibody injection, profound defects in syncytial blastoderm organization occur. This disorganization is seen as aberrant nuclear morphology and position and is suggestive of failures in cytoskeletal function. Nuclear defects correlate with gross defects in the actin cytoskeleton, including indistinct actin caps and furrows, missing actin structures, abnormal spacing of caps, and abnormally spaced furrows. Three-dimensional examination of embryos injected with anti-95F myosin antibody reveals that actin furrows do not invaginate as deeply into the embryo as do normal furrows. These furrows do not separate adjacent mitoses, since microtubules cross over them. These inappropriate microtubule interactions lead to aberrant nuclear divisions and to the nuclear defects observed. We propose that 95F myosin function is required to generate normal actin-based transient membrane furrows. The motor activity of 95F myosin itself and/or components within the particles transported to the furrows by 95F myosin may be required for normal furrows to form.


1997 ◽  
Vol 137 (2) ◽  
pp. 399-416 ◽  
Author(s):  
Kathryn R. Ayscough ◽  
Joel Stryker ◽  
Navin Pokala ◽  
Miranda Sanders ◽  
Phil Crews ◽  
...  

We report that the actin assembly inhibitor latrunculin-A (LAT-A) causes complete disruption of the yeast actin cytoskeleton within 2–5 min, suggesting that although yeast are nonmotile, their actin filaments undergo rapid cycles of assembly and disassembly in vivo. Differences in the LAT-A sensitivities of strains carrying mutations in components of the actin cytoskeleton suggest that tropomyosin, fimbrin, capping protein, Sla2p, and Srv2p act to increase actin cytoskeleton stability, while End3p and Sla1p act to decrease stability. Identification of three LAT-A resistant actin mutants demonstrated that in vivo effects of LAT-A are due specifically to impairment of actin function and implicated a region on the three-dimensional actin structure as the LAT-A binding site. LAT-A was used to determine which of 19 different proteins implicated in cell polarity development require actin to achieve polarized localization. Results show that at least two molecular pathways, one actindependent and the other actin-independent, underlie polarity development. The actin-dependent pathway localizes secretory vesicles and a putative vesicle docking complex to sites of cell surface growth, providing an explanation for the dependence of polarized cell surface growth on actin function. Unexpectedly, several proteins that function with actin during cell polarity development, including an unconventional myosin (Myo2p), calmodulin, and an actin-interacting protein (Bud6/Aip3p), achieved polarized localization by an actin-independent pathway, revealing interdependence among cell polarity pathways. Finally, transient actin depolymerization caused many cells to abandon one bud site or mating projection and to initiate growth at a second site. Thus, actin filaments are also required for maintenance of an axis of cell polarity.


2016 ◽  
Vol 27 (16) ◽  
pp. 2519-2522 ◽  
Author(s):  
Pekka Lappalainen

The actin cytoskeleton supports a vast number of cellular processes in nonmuscle cells. It is well established that the organization and dynamics of the actin cytoskeleton are controlled by a large array of actin-binding proteins. However, it was only 40 years ago that the first nonmuscle actin-binding protein, filamin, was identified and characterized. Filamin was shown to bind and cross-link actin filaments into higher-order structures and contribute to phagocytosis in macrophages. Subsequently many other nonmuscle actin-binding proteins were identified and characterized. These proteins regulate almost all steps of the actin filament assembly and disassembly cycles, as well as the arrangement of actin filaments into diverse three-dimensional structures. Although the individual biochemical activities of most actin-regulatory proteins are relatively well understood, knowledge of how these proteins function together in a common cytoplasm to control actin dynamics and architecture is only beginning to emerge. Furthermore, understanding how signaling pathways and mechanical cues control the activities of various actin-binding proteins in different cellular, developmental, and pathological processes will keep researchers busy for decades.


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