Intracellular signaling events at the leading edge of migrating cells

2000 ◽  
Vol 32 (9) ◽  
pp. 931-943 ◽  
Author(s):  
A.A. Maghazachi
Keyword(s):  
Intracellular Signaling ◽  
Leading Edge ◽  
Signaling Events ◽  
Migrating Cells

scholarly journals The novel RacE-binding protein GflB sharpens Ras activity at the leading edge of migrating cells

2016 ◽  
Vol 27 (10) ◽  
pp. 1596-1605 ◽  
Author(s):  
Hiroshi Senoo ◽  
Huaqing Cai ◽  
Yu Wang ◽  
Hiromi Sesaki ◽  
Miho Iijima
Keyword(s):  
Rho Gtpases ◽  
Rho Gtpase ◽  
Gene Knockout ◽  
Binding Protein ◽  
Affinity Purification ◽  
Leading Edge ◽  
The Novel ◽  
Gradient Sensing ◽  
Signaling Events ◽  
Migrating Cells

Directional sensing, a process in which cells convert an external chemical gradient into internal signaling events, is essential in chemotaxis. We previously showed that a Rho GTPase, RacE, regulates gradient sensing in Dictyostelium cells. Here, using affinity purification and mass spectrometry, we identify a novel RacE-binding protein, GflB, which contains a Ras GEF domain and a Rho GAP domain. Using biochemical and gene knockout approaches, we show that GflB balances the activation of Ras and Rho GTPases, which enables cells to precisely orient signaling events toward higher concentrations of chemoattractants. Furthermore, we find that GflB is located at the leading edge of migrating cells, and this localization is regulated by the actin cytoskeleton and phosphatidylserine. Our findings provide a new molecular mechanism that connects directional sensing and morphological polarization.

scholarly journals Protein Tyrosine Phosphatase-PEST and β8 Integrin Regulate Spatiotemporal Patterns of RhoGDI1 Activation in Migrating Cells

2015 ◽  
Vol 35 (8) ◽  
pp. 1401-1413 ◽  
Author(s):  
Hye Shin Lee ◽  
Mujeeburahiman Cheerathodi ◽  
Sankar P. Chaki ◽  
Steve B. Reyes ◽  
Yanhua Zheng ◽  
...  
Keyword(s):  
Cell Motility ◽  
Protein Tyrosine Phosphatase ◽  
Protein Complexes ◽  
Tyrosine Phosphatase ◽  
Leading Edge ◽  
Protein Tyrosine ◽  
Motile Cells ◽  
Signaling Events ◽  
Gdp Dissociation Inhibitor ◽  
Migrating Cells

Directional cell motility is essential for normal development and physiology, although how motile cells spatiotemporally activate signaling events remains largely unknown. Here, we have characterized an adhesion and signaling unit comprised of protein tyrosine phosphatase (PTP)-PEST and the extracellular matrix (ECM) adhesion receptor β8 integrin that plays essential roles in directional cell motility. β8 integrin and PTP-PEST form protein complexes at the leading edge of migrating cells and balance patterns of Rac1 and Cdc42 signaling by controlling the subcellular localization and phosphorylation status of Rho GDP dissociation inhibitor 1 (RhoGDI1). Translocation of Src-phosphorylated RhoGDI1 to the cell's leading edge promotes local activation of Rac1 and Cdc42, whereas dephosphorylation of RhoGDI1 by integrin-bound PTP-PEST promotes RhoGDI1 release from the membrane and sequestration of inactive Rac1/Cdc42 in the cytoplasm. Collectively, these data reveal a finely tuned regulatory mechanism for controlling signaling events at the leading edge of directionally migrating cells.

scholarly journals Molecular Regulation of Actin Turnover at the Leading Edge of Migrating Cells

2015 ◽  
Vol 108 (2) ◽  
pp. 179a-180a
Author(s):  
Brannon R. McCullough ◽  
David J. Odde
Keyword(s):  
Leading Edge ◽  
Molecular Regulation ◽  
Actin Turnover ◽  
Migrating Cells

scholarly journals Subcellular optogenetic activation of Cdc42 controls local and distal signaling to drive immune cell migration

2016 ◽  
Vol 27 (9) ◽  
pp. 1442-1450 ◽  
Author(s):  
Patrick R. O’Neill ◽  
Vani Kalyanaraman ◽  
N. Gautam
Keyword(s):  
Cell Migration ◽  
Intracellular Signaling ◽  
Immune Cell ◽  
Leading Edge ◽  
Signaling Networks ◽  
Membrane Protrusions ◽  
A Cell ◽  
Immune Cell Migration ◽  
Directional Cell Migration ◽  
Rhoa Signaling

Migratory immune cells use intracellular signaling networks to generate and orient spatially polarized responses to extracellular cues. The monomeric G protein Cdc42 is believed to play an important role in controlling the polarized responses, but it has been difficult to determine directly the consequences of localized Cdc42 activation within an immune cell. Here we used subcellular optogenetics to determine how Cdc42 activation at one side of a cell affects both cell behavior and dynamic molecular responses throughout the cell. We found that localized Cdc42 activation is sufficient to generate polarized signaling and directional cell migration. The optically activated region becomes the leading edge of the cell, with Cdc42 activating Rac and generating membrane protrusions driven by the actin cytoskeleton. Cdc42 also exerts long-range effects that cause myosin accumulation at the opposite side of the cell and actomyosin-mediated retraction of the cell rear. This process requires the RhoA-activated kinase ROCK, suggesting that Cdc42 activation at one side of a cell triggers increased RhoA signaling at the opposite side. Our results demonstrate how dynamic, subcellular perturbation of an individual signaling protein can help to determine its role in controlling polarized cellular responses.

scholarly journals Electric Fields and Inflammation: May the Force be with You

2008 ◽  
Vol 8 ◽  
pp. 1280-1294 ◽  
Author(s):  
Simon B. Brown ◽  
Ian Dransfield
Keyword(s):  
Cell Adhesion ◽  
Electric Fields ◽  
Conformational Changes ◽  
Intracellular Signaling ◽  
Tissue Injury ◽  
Potassium Efflux ◽  
Ample Evidence ◽  
Surface Receptors ◽  
Signaling Events ◽  
A Site

Integrins are a family of ubiquitous cell surface receptors comprising heterodimers of β and α chains that are required for cell adhesion and motility. Integrin-dependent adhesion and signaling is associated with major conformational changes in the ectodomain as it shifts from a low-affinity “bent” to a high-affinity “extended” structure. The ability of a cell to regulate dynamically the affinity or activation state of an integrin, and hence its binding to extracellular matrix or cell adhesion molecules, is assumed to be driven by intracellular signaling events transmitted by protein binding to the cytoplasmic tail. The binding of an integrin to its ligand can then transmit signals back into the cell to regulate the formation of a macromolecular focal adhesion complex that effectively anchors the cytoskeleton to the adhesion site. Many proteins have been reported to associate physically and functionally with integrins, leading to altered signaling events. A particularly intriguing molecular association exists between integrins and transmembrane proteins that gate the movement of charge, especially voltage-gated potassium channels, although the significance of this interaction is not understood. Although ample evidence indicates that the engagement of integrins can promote potassium efflux by both excitable and nonexcitable cells, we speculate the converse, that the activation state of integrins is dynamically regulated by changes in a transmembrane potential. In this way, direct-current electric fields generated at a site of tissue injury can promote the galvanotaxis or directed migration of cells involved in tissue repair and inflammation.

scholarly journals Clathrin-independent carriers form a high capacity endocytic sorting system at the leading edge of migrating cells

2010 ◽  
Vol 190 (4) ◽  
pp. 675-691 ◽  
Author(s):  
Mark T. Howes ◽  
Matthew Kirkham ◽  
James Riches ◽  
Katia Cortese ◽  
Piers J. Walser ◽  
...  
Keyword(s):  
High Capacity ◽  
Leading Edge ◽  
Cellular Adhesion ◽  
Endocytic Pathway ◽  
Membrane Turnover ◽  
Major Pathway ◽  
Endocytic Sorting ◽  
And Migration ◽  
Sorting Station ◽  
Migrating Cells

Although the importance of clathrin- and caveolin-independent endocytic pathways has recently emerged, key aspects of these routes remain unknown. Using quantitative ultrastructural approaches, we show that clathrin-independent carriers (CLICs) account for approximately three times the volume internalized by the clathrin-mediated endocytic pathway, forming the major pathway involved in uptake of fluid and bulk membrane in fibroblasts. Electron tomographic analysis of the 3D morphology of the earliest carriers shows that they are multidomain organelles that form a complex sorting station as they mature. Proteomic analysis provides direct links between CLICs, cellular adhesion turnover, and migration. Consistent with this, CLIC-mediated endocytosis of key cargo proteins, CD44 and Thy-1, is polarized at the leading edge of migrating fibroblasts, while transient ablation of CLICs impairs their ability to migrate. These studies provide the first quantitative ultrastructural analysis and molecular characterization of the major endocytic pathway in fibroblasts, a pathway that provides rapid membrane turnover at the leading edge of migrating cells.

scholarly journals Integrin-mediated Protein Kinase A Activation at the Leading Edge of Migrating Cells

2008 ◽  
Vol 19 (11) ◽  
pp. 4930-4941 ◽  
Author(s):  
Chinten J. Lim ◽  
Kristin H. Kain ◽  
Eugene Tkachenko ◽  
Lawrence E. Goldfinger ◽  
Edgar Gutierrez ◽  
...  
Keyword(s):  
Cell Migration ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Leading Edge ◽  
Pi3 Kinase ◽  
Early Event ◽  
Type I ◽  
Cell Protrusion ◽  
Kinase A ◽  
Migrating Cells

cAMP-dependent protein kinase A (PKA) is important in processes requiring localized cell protrusion, such as cell migration and axonal path finding. Here, we used a membrane-targeted PKA biosensor to reveal activation of PKA at the leading edge of migrating cells. Previous studies show that PKA activity promotes protrusion and efficient cell migration. In live migrating cells, membrane-associated PKA activity was highest at the leading edge and required ligation of integrins such as α4β1 or α5β1 and an intact actin cytoskeleton. α4 integrins are type I PKA-specific A-kinase anchoring proteins, and we now find that type I PKA is important for localization of α4β1 integrin-mediated PKA activation at the leading edge. Accumulation of 3′ phosphorylated phosphoinositides [PtdIns(3,4,5)P3] products of phosphatidylinositol 3-kinase (PI3-kinase) is an early event in establishing the directionality of migration; however, polarized PKA activation did not require PI3-kinase activity. Conversely, inhibition of PKA blocked accumulation of a PtdIns(3,4,5)P3-binding protein, the AKT-pleckstrin homology (PH) domain, at the leading edge; hence, PKA is involved in maintaining cell polarity during migration. In sum, we have visualized compartment-specific PKA activation in migrating cells and used it to reveal that adhesion-mediated localized activation of PKA is an early step in directional cell migration.

scholarly journals TRPV4-mediated calcium signaling in mesenchymal stem cells regulates aligned collagen matrix formation and vinculin tension

2019 ◽  
Vol 116 (6) ◽  
pp. 1992-1997 ◽  
Author(s):  
Christopher L. Gilchrist ◽  
Holly A. Leddy ◽  
Laurel Kaye ◽  
Natasha D. Case ◽  
Katheryn E. Rothenberg ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Intracellular Signaling ◽  
Collagen Matrix ◽  
Transient Receptor Potential Vanilloid ◽  
Fibrillar Collagen ◽  
Matrix Assembly ◽  
Collagen Formation ◽  
Signaling Events

Microarchitectural cues drive aligned fibrillar collagen deposition in vivo and in biomaterial scaffolds, but the cell-signaling events that underlie this process are not well understood. Utilizing a multicellular patterning model system that allows for observation of intracellular signaling events during collagen matrix assembly, we investigated the role of calcium (Ca2+) signaling in human mesenchymal stem cells (MSCs) during this process. We observed spontaneous Ca2+oscillations in MSCs during fibrillar collagen assembly, and hypothesized that the transient receptor potential vanilloid 4 (TRPV4) ion channel, a mechanosensitive Ca2+-permeable channel, may regulate this signaling. Inhibition of TRPV4 nearly abolished Ca2+signaling at initial stages of collagen matrix assembly, while at later times had reduced but significant effects. Importantly, blocking TRPV4 activity dramatically reduced aligned collagen fibril assembly; conversely, activating TRPV4 accelerated aligned collagen formation. TRPV4-dependent Ca2+oscillations were found to be independent of pattern shape or subpattern cell location, suggesting this signaling mechanism is necessary for aligned collagen formation but not sufficient in the absence of physical (microarchitectural) cues that force multicellular alignment. As cell-generated mechanical forces are known to be critical to the matrix assembly process, we examined the role of TRPV4-mediated Ca2+signaling in force generated across the load-bearing focal adhesion protein vinculin within MSCs using an FRET-based tension sensor. Inhibiting TRPV4 decreased tensile force across vinculin, whereas TRPV4 activation caused a dynamic unloading and reloading of vinculin. Together, these findings suggest TRPV4 activity regulates forces at cell-matrix adhesions and is critical to aligned collagen matrix assembly by MSCs.

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