scholarly journals Extracellular signalling modulates Scar/WAVE complex activity through Abi phosphorylation

2021 ◽  
Author(s):  
Shashi Prakash Singh ◽  
Peter Thomason ◽  
Robert Insall
Keyword(s):  
Cell Migration ◽  
Environmental Cues ◽  
Complex Activity ◽  
Extracellular Signals ◽  
Substrate Adhesion ◽  
Cell Substrate ◽  
Environmental Responses ◽  
Cell Substrate Adhesion ◽  
Extracellular Signalling ◽  
Wave Complex

The lamellipodia and pseudopodia of migrating cells are produced and maintained by the Scar/WAVE complex. Thus, actin-based cell migration is largely controlled through regulation of Scar/WAVE. Here we report that the Abi subunit - not Scar/WAVE - is phosphorylated in response to extracellular signalling. Like Scar, Abi is phosphorylated after the complex has been activated, implying that Abi phosphorylation modulates pseudopodia, rather than causing new ones to be made. Consistent with this, Scar/WAVE complex mutants that cannot bind Rac are also not phosphorylated. Several environmental cues also affect Abi phosphorylation - cell-substrate adhesion promotes it and increased extracellular osmolarity diminishes it. Both unphosphorylatable and phosphomimetic Abi efficiently rescue the chemotaxis of Abi KO cells and pseudopodia formation, confirming that Abi phosphorylation is not required for activation or inactivation of the Scar/WAVE complex. However, pseudopodia and Scar/WAVE patches in the cells with unphosphorylatable Abi protrude for longer, altering pseudopod dynamics and cell speed. Cells in which Scar and Abi are both unphosphorylatable can still form pseudopods, but migrate substantially faster. We conclude that extracellular signals and environmental responses modulate cell migration by tuning the behaviour of the Scar/WAVE complex after it has been activated.

scholarly journals Extracellular Signalling Modulates Scar/WAVE Complex Activity through Abi Phosphorylation

Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3485
Author(s):  
Shashi Prakash Singh ◽  
Peter A. Thomason ◽  
Robert H. Insall
Keyword(s):  
Cell Migration ◽  
Environmental Cues ◽  
Complex Activity ◽  
Extracellular Signals ◽  
Substrate Adhesion ◽  
Cell Substrate ◽  
Environmental Responses ◽  
Cell Substrate Adhesion ◽  
Extracellular Signalling ◽  
Wave Complex

The lamellipodia and pseudopodia of migrating cells are produced and maintained by the Scar/WAVE complex. Thus, actin-based cell migration is largely controlled through regulation of Scar/WAVE. Here, we report that the Abi subunit—but not Scar—is phosphorylated in response to extracellular signalling in Dictyostelium cells. Like Scar, Abi is phosphorylated after the complex has been activated, implying that Abi phosphorylation modulates pseudopodia, rather than causing new ones to be made. Consistent with this, Scar complex mutants that cannot bind Rac are also not phosphorylated. Several environmental cues also affect Abi phosphorylation—cell-substrate adhesion promotes it and increased extracellular osmolarity diminishes it. Both unphosphorylatable and phosphomimetic Abi efficiently rescue the chemotaxis of Abi KO cells and pseudopodia formation, confirming that Abi phosphorylation is not required for activation or inactivation of the Scar/WAVE complex. However, pseudopodia and Scar patches in the cells with unphosphorylatable Abi protrude for longer, altering pseudopod dynamics and cell speed. Dictyostelium, in which Scar and Abi are both unphosphorylatable, can still form pseudopods, but migrate substantially faster. We conclude that extracellular signals and environmental responses modulate cell migration by tuning the behaviour of the Scar/WAVE complex after it has been activated.

scholarly journals Cell-substrate adhesion drives Scar/WAVE activation and phosphorylation, which controls pseudopod lifetime

2019 ◽  
Author(s):  
Shashi Prakash Singh ◽  
Peter A. Thomason ◽  
Sergio Lilla ◽  
Matthias Schaks ◽  
Qing Tang ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Extracellular Signals ◽  
Rich Domain ◽  
Substrate Adhesion ◽  
Cell Substrate ◽  
Cell Substrate Adhesion ◽  
Wave Complex

AbstractThe Scar/WAVE complex is the principal catalyst of pseudopod and lamellipod formation. Here we show that Scar/WAVE’s proline-rich domain is polyphosphorylated after the complex is activated. Treatments that stop activation block phosphorylation in both Dictyostelium and mammalian cells. This implies that phosphorylation modulates pseudopods after they have been formed, rather than controlling whether a protrusion is initiated. Unexpectedly, activation-dependent phosphorylation is not promoted by chemotactic signalling, or by signal-dependent kinases such as ERKs, but is greatly stimulated by cell:substrate adhesion. Scar/WAVE that has been mutated to be either unphosphorylatable or phosphomimetic is activated normally, and rescues the phenotype of scar− cells, demonstrating that phosphorylation is dispensible for activation and actin regulation. However, pseudopods and patches of Scar/WAVE complex recruitment last substantially longer in unphosphorylatable mutants, altering cell polarisation and the efficiency of migration. We conclude that pseudopod engagement with substratum is more important than extracellular signals at regulating Scar/WAVE’s activity, and that phosphorylation acts as a timer, restricting pseudopod lifetime by promoting Scar/WAVE turnover.

scholarly journals The crosstalk between microtubules, actin and membranes shapes cell division

Open Biology ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 190314 ◽  
Author(s):  
Francesca Rizzelli ◽  
Maria Grazia Malabarba ◽  
Sara Sigismund ◽  
Marina Mapelli
Keyword(s):  
Membrane Trafficking ◽  
Mitotic Progression ◽  
Isolated Cells ◽  
Spindle Positioning ◽  
Substrate Adhesion ◽  
Cell Substrate ◽  
Epithelial Sheets ◽  
Cell Substrate Adhesion ◽  
Extracellular Signalling

Mitotic progression is orchestrated by morphological and mechanical changes promoted by the coordinated activities of the microtubule (MT) cytoskeleton, the actin cytoskeleton and the plasma membrane (PM). MTs assemble the mitotic spindle, which assists sister chromatid separation, and contact the rigid and tensile actomyosin cortex rounded-up underneath the PM. Here, we highlight the dynamic crosstalk between MTs, actin and cell membranes during mitosis, and discuss the molecular connections between them. We also summarize recent views on how MT traction forces, the actomyosin cortex and membrane trafficking contribute to spindle positioning in isolated cells in culture and in epithelial sheets. Finally, we describe the emerging role of membrane trafficking in synchronizing actomyosin tension and cell shape changes with cell–substrate adhesion, cell–cell contacts and extracellular signalling events regulating proliferation.

scholarly journals The interplay of cell–cell and cell–substrate adhesion in collective cell migration

2014 ◽  
Vol 11 (100) ◽  
pp. 20140684 ◽  
Author(s):  
Chenlu Wang ◽  
Sagar Chowdhury ◽  
Meghan Driscoll ◽  
Carole A. Parent ◽  
S. K. Gupta ◽  
...  
Keyword(s):  
Cell Migration ◽  
Cell Surface ◽  
Actin Polymerization ◽  
Collective Cell Migration ◽  
Cell Contacts ◽  
Substrate Adhesion ◽  
Cell Substrate ◽  
Cell Shapes ◽  
Cell Substrate Adhesion ◽  
Cell Cell

Collective cell migration often involves notable cell–cell and cell–substrate adhesions and highly coordinated motion of touching cells. We focus on the interplay between cell–substrate adhesion and cell–cell adhesion. We show that the loss of cell-surface contact does not significantly alter the dynamic pattern of protrusions and retractions of fast migrating amoeboid cells ( Dictyostelium discoideum ), but significantly changes their ability to adhere to other cells. Analysis of the dynamics of cell shapes reveals that cells that are adherent to a surface may coordinate their motion with neighbouring cells through protrusion waves that travel across cell–cell contacts. However, while shape waves exist if cells are detached from surfaces, they do not couple cell to cell. In addition, our investigation of actin polymerization indicates that loss of cell-surface adhesion changes actin polymerization at cell–cell contacts. To further investigate cell–cell/cell–substrate interactions, we used optical micromanipulation to form cell–substrate contact at controlled locations. We find that both cell-shape dynamics and cytoskeletal activity respond rapidly to the formation of cell–substrate contact.

scholarly journals A Stochastic Modelling Framework for Single Cell Migration: Coupling Contractility and Focal Adhesions

Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1348
Author(s):  
Aydar Uatay
Keyword(s):  
Cell Migration ◽  
Cell Motility ◽  
Focal Adhesions ◽  
Stochastic Modelling ◽  
Modelling Framework ◽  
Substrate Adhesion ◽  
Actomyosin Contractility ◽  
Motile Cells ◽  
Cell Substrate ◽  
Cell Substrate Adhesion

The interaction of the actin cytoskeleton with cell–substrate adhesions is necessary for cell migration. While the trajectories of motile cells have a stochastic character, investigations of cell motility mechanisms rarely elaborate on the origins of the observed randomness. Here, guided by a few fundamental attributes of cell motility, I construct a minimal stochastic cell migration model from ground-up. The resulting model couples a deterministic actomyosin contractility mechanism with stochastic cell–substrate adhesion kinetics, and yields a well-defined piecewise deterministic process. Numerical simulations reproduce several experimentally observed results, including anomalous diffusion, tactic migration and contact guidance. This work provides a basis for the development of cell–cell collision and population migration models.

scholarly journals Regulation of cell-substrate adhesion by proteoglycans immobilized on extracellular substrates

1989 ◽  
Vol 264 (14) ◽  
pp. 8012-8018 ◽  
Author(s):  
M Yamagata ◽  
S Suzuki ◽  
S K Akiyama ◽  
K M Yamada ◽  
K Kimata
Keyword(s):  
Substrate Adhesion ◽  
Cell Substrate ◽  
Cell Substrate Adhesion

scholarly journals A GTPase controls cell-substrate adhesion in Xenopus XTC fibroblasts.

1992 ◽  
Vol 118 (5) ◽  
pp. 1235-1244 ◽  
Author(s):  
M H Symons ◽  
T J Mitchison
Keyword(s):  
Control Cell ◽  
Response To Treatment ◽  
Nucleotide Analogs ◽  
Cell Contractility ◽  
Cell Rounding ◽  
Substrate Adhesion ◽  
Cell Substrate ◽  
Adhesive Interactions ◽  
Cell Substrate Adhesion ◽  
Gamma S

Cell-substrate adhesion is crucial at various stages of development and for the maintenance of normal tissues. Little is known about the regulation of these adhesive interactions. To investigate the role of GTPases in the control of cell morphology and cell-substrate adhesion we have injected guanine nucleotide analogs into Xenopus XTC fibroblasts. Injection of GTP gamma S inhibited ruffling and increased spreading, suggesting an increase in adhesion. To further investigate this, we made use of GRGDSP, a peptide which inhibits binding of integrins to vitronectin and fibronectin. XTC fibroblasts injected with non-hydrolyzable analogs of GTP took much more time to round up than mock-injected cells in response to treatment with GRGDSP, while GDP beta S-injected cells rounded up in less time than controls. Injection with GTP gamma S did not inhibit cell rounding induced by trypsin however, showing that cell contractility is not significantly affected by the activation of GTPases. These data provide evidence for the existence of a GTPase which can control cell-substrate adhesion from the cytoplasm. Treatment of XTC fibroblasts with the phorbol ester 12-o-tetradecanoylphorbol-13-acetate reduced cell spreading and accelerated cell rounding in response to GRGDSP, which is essentially opposite to the effect exerted by non-hydrolyzable GTP analogs. These results suggest the existence of at least two distinct pathways controlling cell-substrate adhesion in XTC fibroblasts, one depending on a GTPase and another one involving protein kinase C.

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