A chemorepellent inhibits local Ras activation to inhibit pseudopod formation to bias cell movement away from the chemorepellent

2021 ◽  
Author(s):  
Sara A. Kirolos ◽  
Richard H. Gomer
Keyword(s):  
G Protein ◽  
Cell Movement ◽  
Cortical Activation ◽  
Cell Cortex ◽  
Ras Proteins ◽  
Ras Protein ◽  
Chemical Gradients ◽  
Ras Activation ◽  
Extracellular Signal ◽  
A Cell

The ability of cells to sense chemical gradients is essential during development, morphogenesis, and immune responses. Although much is known about chemoattraction, chemorepulsion remains poorly understood. Proliferating Dictyostelium cells secrete a chemorepellent protein called AprA. AprA prevents pseudopod formation at the region of the cell closest to the source of AprA, causing the random movement of cells to be biased away from the AprA. Activation of Ras proteins in a localized sector of a cell cortex helps to induce pseudopod formation, and Ras proteins are needed for AprA chemorepulsion. Here we show that AprA locally inhibits Ras cortical activation through the G protein-coupled receptor GrlH, the G protein subunits Gβ and Gα8, Ras protein RasG, protein kinase B, the p-21 activated kinase PakD, and the extracellular signal-regulated kinase Erk1. Diffusion calculations and experiments indicate that in a colony of cells, high extracellular concentrations of AprA in the center can globally inhibit Ras activation, while a gradient of AprA that naturally forms at the edge of the colony allow cells to activate Ras at sectors of the cell other than the sector of the cell closest to the center of the colony, effectively inducing both repulsion from the colony and cell differentiation. Together, these results suggest that a pathway that inhibits local Ras activation can mediate chemorepulsion. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text]

scholarly journals Role of receptor tyrosine kinases in G-protein-coupled receptor regulation of Ras: transactivation or parallel pathways?

2003 ◽  
Vol 376 (1) ◽  
pp. e9-e10 ◽  
Author(s):  
Julian DOWNWARD
Keyword(s):  
G Protein ◽  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Growth Factor Receptor ◽  
Nucleotide Exchange ◽  
Lpa Receptor ◽  
Ras Protein ◽  
Ras Activation ◽  
Epidermal Growth ◽  
G Protein Coupled

Ras protein regulation by G-protein-coupled receptors has been thought to occur through transactivation of receptor tyrosine kinases. New evidence suggests that these two receptor types independently control different pathways leading to Ras activation in response to lysophosphatidic acid (LPA). Epidermal growth factor receptor function is needed for basal nucleotide exchange on Ras, whereas the LPA receptor controls an inducible exchange activity.

scholarly journals Dictyostelium RasG Is Required for Normal Motility and Cytokinesis, But Not Growth

1997 ◽  
Vol 138 (3) ◽  
pp. 605-614 ◽  
Author(s):  
Richard I. Tuxworth ◽  
Janet L. Cheetham ◽  
Laura M. Machesky ◽  
George B. Spiegelmann ◽  
Gerald Weeks ◽  
...  
Keyword(s):  
Cell Polarity ◽  
Cell Movement ◽  
Ras Proteins ◽  
Wild Type ◽  
Principal Role ◽  
Ras Protein ◽  
Wide Range ◽  
And Control ◽  
Mutant Cells ◽  
Lamellipodia Formation

RasG is the most abundant Ras protein in growing Dictyostelium cells and the closest relative of mammalian Ras proteins. We have generated null mutants in which expression of RasG is completely abolished. Unexpectedly, RasG− cells are able to grow at nearly wild-type rates. However, they exhibit defective cell movement and a wide range of defects in the control of the actin cytoskeleton, including a loss of cell polarity, absence of normal lamellipodia, formation of unusual small, punctate polymerized actin structures, and a large number of abnormally long filopodia. Despite their lack of polarity and abnormal cytoskeleton, mutant cells perform normal chemotaxis. However, rasG− cells are unable to perform normal cytokinesis, becoming multinucleate when grown in suspension culture. Taken together, these data suggest a principal role for RasG in coordination of cell movement and control of the cytoskeleton.

scholarly journals An endogenous chemorepellent directs cell movement by inhibiting pseudopods at one side of cells

2019 ◽  
Vol 30 (2) ◽  
pp. 242-255 ◽  
Author(s):  
Ramesh Rijal ◽  
Kristen M. Consalvo ◽  
Christopher K. Lindsey ◽  
Richard H. Gomer
Keyword(s):  
Signal Transduction ◽  
Actin Polymerization ◽  
Formation Rate ◽  
Cell Movement ◽  
Signal Transduction Pathway ◽  
Pi3 Kinase ◽  
Signal Transduction Pathways ◽  
Ras Protein ◽  
A Cell ◽  
G Protein Coupled

Eukaryotic chemoattraction signal transduction pathways, such as those used by Dictyostelium discoideum to move toward cAMP, use a G protein–coupled receptor to activate multiple conserved pathways such as PI3 kinase/Akt/PKB to induce actin polymerization and pseudopod formation at the front of a cell, and PTEN to localize myosin II to the rear of a cell. Relatively little is known about chemorepulsion. We previously found that AprA is a chemorepellent protein secreted by Dictyostelium cells. Here we used 29 cell lines with disruptions of cAMP and/or AprA signal transduction pathway components, and delineated the AprA chemorepulsion pathway. We find that AprA uses a subset of chemoattraction signal transduction pathways including Ras, protein kinase A, target of rapamycin (TOR), phospholipase A, and ERK1, but does not require the PI3 kinase/Akt/PKB and guanylyl cyclase pathways to induce chemorepulsion. Possibly as a result of not using the PI3 kinase/Akt/PKB pathway and guanylyl cyclases, AprA does not induce actin polymerization or increase the pseudopod formation rate, but rather appears to inhibit pseudopod formation at the side of cells closest to the source of AprA.

scholarly journals Coupled excitable Ras and F-actin activation mediates spontaneous pseudopod formation and directed cell movement

2017 ◽  
Vol 28 (7) ◽  
pp. 922-934 ◽  
Author(s):  
Peter J. M. van Haastert ◽  
Ineke Keizer-Gunnink ◽  
Arjan Kortholt
Keyword(s):  
Cell Movement ◽  
Back Side ◽  
Sensitive Assay ◽  
Genetic Studies ◽  
Excitable System ◽  
Chemical Gradients ◽  
Ras Activation ◽  
Excitable Systems ◽  
External Cues ◽  
Sense And Respond

Many eukaryotic cells regulate their mobility by external cues. Genetic studies have identified >100 components that participate in chemotaxis, which hinders the identification of the conceptual framework of how cells sense and respond to shallow chemical gradients. The activation of Ras occurs during basal locomotion and is an essential connector between receptor and cytoskeleton during chemotaxis. Using a sensitive assay for activated Ras, we show here that activation of Ras and F-actin forms two excitable systems that are coupled through mutual positive feedback and memory. This coupled excitable system leads to short-lived patches of activated Ras and associated F-actin that precede the extension of protrusions. In buffer, excitability starts frequently with Ras activation in the back/side of the cell or with F-actin in the front of the cell. In a shallow gradient of chemoattractant, local Ras activation triggers full excitation of Ras and subsequently F-actin at the side of the cell facing the chemoattractant, leading to directed pseudopod extension and chemotaxis. A computational model shows that the coupled excitable Ras/F-actin system forms the driving heart for the ordered-stochastic extension of pseudopods in buffer and for efficient directional extension of pseudopods in chemotactic gradients.

G-protein-coupled receptors signalling at the cell nucleus: an emerging paradigmThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 287-297 ◽  
Author(s):  
Fernand Gobeil ◽  
Audrey Fortier ◽  
Tang Zhu ◽  
Michela Bossolasco ◽  
Martin Leduc ◽  
...  
Keyword(s):  
G Protein ◽  
Cell Nucleus ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Nuclear Translocation ◽  
Cell Metabolism ◽  
Hormone Secretion ◽  
G Protein Coupled Receptors ◽  
A Cell ◽  
G Protein Coupled

G-protein-coupled receptors (GPCRs) comprise a wide family of monomeric heptahelical glycoproteins that recognize a broad array of extracellular mediators including cationic amines, lipids, peptides, proteins, and sensory agents. Thus far, much attention has been given towards the comprehension of intracellular signaling mechanisms activated by cell membrane GPCRs, which convert extracellular hormonal stimuli into acute, non-genomic (e.g., hormone secretion, muscle contraction, and cell metabolism) and delayed, genomic biological responses (e.g., cell division, proliferation, and apoptosis). However, with respect to the latter response, there is compelling evidence for a novel intracrine mode of genomic regulation by GPCRs that implies either the endocytosis and nuclear translocation of peripheral-liganded GPCR and (or) the activation of nuclearly located GPCR by endogenously produced, nonsecreted ligands. A noteworthy example of the last scenario is given by heptahelical receptors that are activated by bioactive lipoids (e.g., PGE2 and PAF), many of which may be formed from bilayer membranes including those of the nucleus. The experimental evidence for the nuclear localization and signalling of GPCRs will be reviewed. We will also discuss possible molecular mechanisms responsible for the atypical compartmentalization of GPCRs at the cell nucleus, along with their role in gene expression.

Inhibition by phospholipids of the interaction between R-ras, rho, and their GTPase-activating proteins

1989 ◽  
Vol 9 (11) ◽  
pp. 5260-5264
Author(s):  
M H Tsai ◽  
A Hall ◽  
D W Stacey
Keyword(s):  
Ras Proteins ◽  
Ras Protein ◽  
Gtpase Activating Proteins ◽  
Related Proteins

Certain lipids were found to inhibit the interaction between rho and R-ras proteins and their respective GTPase-activating proteins (GAP). Inhibitory lipids were similar for each protein but differed significantly from those previously found to inhibit the interaction between ras protein and GAP activity. These data raise the possibility that ras and related proteins are controlled biologically by interactions between lipids and GAP molecules.

Selective recruitment of arrestin-3 to clathrin coated pits upon stimulation of G protein-coupled receptors

2000 ◽  
Vol 113 (13) ◽  
pp. 2463-2470 ◽  
Author(s):  
F. Santini ◽  
R.B. Penn ◽  
A.W. Gagnon ◽  
J.L. Benovic ◽  
J.H. Keen
Keyword(s):  
G Protein ◽  
G Protein Coupled Receptors ◽  
Coated Pits ◽  
Over Expression ◽  
Physiological Conditions ◽  
A Cell ◽  
G Protein Coupled ◽  
Comparable Magnitude

Non-visual arrestins (arrestin-2 and arrestin-3) play critical roles in the desensitization and internalization of many G protein-coupled receptors. In vitro experiments have shown that both non-visual arrestins bind with high and approximately comparable affinities to activated, phosphorylated forms of receptors. They also exhibit high affinity binding, again of comparable magnitude, to clathrin. Further, agonist-promoted internalization of many receptors has been found to be stimulated by exogenous over-expression of either arrestin2 or arrestin3. The existence of multiple arrestins raises the question whether stimulated receptors are selective for a specific endogenous arrestin under more physiological conditions. Here we address this question in RBL-2H3 cells, a cell line that expresses comparable levels of endogenous arrestin-2 and arrestin-3. When (beta)(2)-adrenergic receptors are stably expressed in these cells the receptors internalize efficiently following agonist stimulation. However, by immunofluorescence microscopy we determine that only arrestin-3, but not arrestin-2, is rapidly recruited to clathrin coated pits upon receptor stimulation. Similarly, in RBL-2H3 cells that stably express physiological levels of m1AChR, the addition of carbachol selectively induces the localization of arrestin-3, but not arrestin-2, to coated pits. Thus, this work demonstrates coupling of G protein-coupled receptors to a specific non-visual arrestin in an in vivo setting.

The 70-kilodalton adenylyl cyclase-associated protein is not essential for interaction of Saccharomyces cerevisiae adenylyl cyclase with RAS proteins

1992 ◽  
Vol 12 (11) ◽  
pp. 4937-4945
Author(s):  
J Wang ◽  
N Suzuki ◽  
T Kataoka
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Weight ◽  
Adenylyl Cyclase ◽  
High Molecular Weight ◽  
Size Difference ◽  
Missense Mutations ◽  
Ras Proteins ◽  
High Molecular Weight Complex ◽  
Ras Protein ◽  
Dependent Activity

In the yeast Saccharomyces cerevisiae, adenylyl cyclase is regulated by RAS proteins. We show here that the yeast adenylyl cyclase forms at least two high-molecular-weight complexes, one with the RAS protein-dependent adenylyl cyclase activity and the other with the Mn(2+)-dependent activity, which are separable by their size difference. The 70-kDa adenylyl cyclase-associated protein (CAP) existed in the former complex but not in the latter. Missense mutations in conserved motifs of the leucine-rich repeats of the catalytic subunit of adenylyl cyclase abolished the RAS-dependent activity, which was accompanied by formation of a very high molecular weight complex having the Mn(2+)-dependent activity. Contrary to previous results, disruption of the gene encoding CAP did not alter the extent of RAS protein-dependent activation of adenylyl cyclase, while a concomitant decrease in the size of the RAS-responsive complex was observed. These results indicate that CAP is not essential for interaction of the yeast adenylyl cyclase with RAS proteins even though it is an inherent component of the RAS-responsive adenylyl cyclase complex.

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