scholarly journals Rho small GTPase regulates the stability of individual focal adhesions: a FRET-based visualization of GDP/GTP exchange on small GTPases

BIOPHYSICS ◽  
2007 ◽  
Vol 3 ◽  
pp. 63-73 ◽  
Author(s):  
Takayuki Miyauchi ◽  
Toshio Yanagida ◽  
Yasushi Sako
Keyword(s):  
Focal Adhesions ◽  
Small Gtpases ◽  
Small Gtpase ◽  
The Stability

scholarly journals Rab18 regulates focal adhesion dynamics by interacting with kinectin-1 at the endoplasmic reticulum

2020 ◽  
Vol 219 (7) ◽  
Author(s):  
Noemi Antonella Guadagno ◽  
Azzurra Margiotta ◽  
Synne Arstad Bjørnestad ◽  
Linda Hofstad Haugen ◽  
Ingrid Kjos ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Focal Adhesion ◽  
Focal Adhesions ◽  
Molecular Switches ◽  
Underlying Mechanism ◽  
Small Gtpases ◽  
Small Gtpase ◽  
Canonical Function ◽  
Dependent Transport

The members of the Rab family of small GTPases are molecular switches that regulate distinct steps in different membrane traffic pathways. In addition to this canonical function, Rabs can play a role in other processes, such as cell adhesion and motility. Here, we reveal the role of the small GTPase Rab18 as a positive regulator of directional migration in chemotaxis, and the underlying mechanism. We show that knockdown of Rab18 reduces the size of focal adhesions (FAs) and influences their dynamics. Furthermore, we found that Rab18, by directly interacting with the endoplasmic reticulum (ER)-resident protein kinectin-1, controls the anterograde kinesin-1–dependent transport of the ER required for the maturation of nascent FAs and protrusion orientation toward a chemoattractant. Altogether, our data support a model in which Rab18 regulates kinectin-1 transport toward the cell surface to form ER–FA contacts, thus promoting FA growth and cell migration during chemotaxis.

scholarly journals CRL5-dependent regulation of the small GTPases ARL4C and ARF6 controls hippocampal morphogenesis

2020 ◽  
Vol 117 (37) ◽  
pp. 23073-23084
Author(s):  
Jisoo S. Han ◽  
Keiko Hino ◽  
Wenzhe Li ◽  
Raenier V. Reyes ◽  
Cesar P. Canales ◽  
...  
Keyword(s):  
Pyramidal Neuron ◽  
Pyramidal Neurons ◽  
Small Gtpases ◽  
Small Gtpase ◽  
Cullin 5 ◽  
Hippocampal Development ◽  
The Stability ◽  
Cytoskeletal Rearrangements ◽  
Apical Dendrites

The small GTPase ARL4C participates in the regulation of cell migration, cytoskeletal rearrangements, and vesicular trafficking in epithelial cells. The ARL4C signaling cascade starts by the recruitment of the ARF–GEF cytohesins to the plasma membrane, which, in turn, bind and activate the small GTPase ARF6. However, the role of ARL4C–cytohesin–ARF6 signaling during hippocampal development remains elusive. Here, we report that the E3 ubiquitin ligase Cullin 5/RBX2 (CRL5) controls the stability of ARL4C and its signaling effectors to regulate hippocampal morphogenesis. Both RBX2 knockout and Cullin 5 knockdown cause hippocampal pyramidal neuron mislocalization and development of multiple apical dendrites. We used quantitative mass spectrometry to show that ARL4C, Cytohesin-1/3, and ARF6 accumulate in the RBX2 mutant telencephalon. Furthermore, we show that depletion of ARL4C rescues the phenotypes caused by Cullin 5 knockdown, whereas depletion of CYTH1 or ARF6 exacerbates overmigration. Finally, we show that ARL4C, CYTH1, and ARF6 are necessary for the dendritic outgrowth of pyramidal neurons to the superficial strata of the hippocampus. Overall, we identified CRL5 as a key regulator of hippocampal development and uncovered ARL4C, CYTH1, and ARF6 as CRL5-regulated signaling effectors that control pyramidal neuron migration and dendritogenesis.

TBC proteins: GAPs for mammalian small GTPase Rab?

2011 ◽  
Vol 31 (3) ◽  
pp. 159-168 ◽  
Author(s):  
Mitsunori Fukuda
Keyword(s):  
Insulin Resistance ◽  
Small Gtpases ◽  
Structure And Function ◽  
Small Gtpase ◽  
Cell Cycle Regulators ◽  
Gtpase Activating Protein ◽  
Domain Family ◽  
Protein Motif ◽  
Conserved Domain ◽  
And Function

The TBC (Tre-2/Bub2/Cdc16) domain was originally identified as a conserved domain among the tre-2 oncogene product and the yeast cell cycle regulators Bub2 and Cdc16, and it is now widely recognized as a conserved protein motif that consists of approx. 200 amino acids in all eukaryotes. Since the TBC domain of yeast Gyps [GAP (GTPase-activating protein) for Ypt proteins] has been shown to function as a GAP domain for small GTPase Ypt/Rab, TBC domain-containing proteins (TBC proteins) in other species are also expected to function as a certain Rab-GAP. More than 40 different TBC proteins are present in humans and mice, and recent accumulating evidence has indicated that certain mammalian TBC proteins actually function as a specific Rab-GAP. Some mammalian TBC proteins {e.g. TBC1D1 [TBC (Tre-2/Bub2/Cdc16) domain family, member 1] and TBC1D4/AS160 (Akt substrate of 160 kDa)} play an important role in homoeostasis in mammals, and defects in them are directly associated with mouse and human diseases (e.g. leanness in mice and insulin resistance in humans). The present study reviews the structure and function of mammalian TBC proteins, especially in relation to Rab small GTPases.

scholarly journals Yersinia enterocolitica Adhesin A Induces Production of Interleukin-8 in Epithelial Cells

2004 ◽  
Vol 72 (12) ◽  
pp. 6780-6789 ◽  
Author(s):  
Yvonne Schmid ◽  
Guntram A. Grassl ◽  
Oliver T. Bühler ◽  
Mikael Skurnik ◽  
Ingo B. Autenrieth ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Yersinia Enterocolitica ◽  
Hela Cells ◽  
Map Kinases ◽  
Small Gtpases ◽  
Small Gtpase ◽  
Interleukin 8 ◽  
Β1 Integrin ◽  
Β1 Integrins ◽  
Tissue Reactions

ABSTRACT The major invasive factor of Yersinia enterocolitica, the invasin (Inv) protein, induces proinflammatory host cell responses, including interleukin-8 (IL-8) secretion from human epithelial cells, by engagement of β1 integrins. The Inv-triggered β1 integrin signaling involves the small GTPase Rac; the activation of MAP kinases, such as p38, MEK1, and JNK; and the activation of the transcription factor NF-κB. In the present study, we demonstrate that Y. enterocolitica YadA, which is a major adhesin of Y. enterocolitica with pleiotropic virulence effects, induces IL-8 secretion in epithelial cells. The abilites of YadA and Inv to promote adhesion to and invasion of HeLa cells and to induce IL-8 production by the cells were investigated by expression of YadA and Inv in Escherichia coli. While YadA mediates efficacious adhesion to HeLa cells, it mediates marginal invasion compared with Inv. Both YadA and Inv trigger comparable levels of IL-8 production. Conformational changes of the YadA head domain by mutation of NSVAIG-S motifs, which abolish collagen binding, also abolish adhesion of Yersinia to HeLa cells and YadA-mediated IL-8 secretion. Furthermore, experiments in which blocking antibodies against β1 integrins were used demonstrate that β1 integrins are crucial for YadA-mediated IL-8 secretion. Inhibitor studies demonstrate the involvement of small GTPases and MAP kinases, such as p38, MEK1, and JNK, indicating that β1 integrin-dependent signaling mediated by Inv or YadA involves similar signaling pathways. These data present YadA, in addition to Inv, YopB, and Yersinia lipopolysaccharide, as a further inducer of proinflammatory molecules by which Y. enterocolitica might promote inflammatory tissue reactions.

scholarly journals The Small GTPase Rap1b: A Bidirectional Regulator of Platelet Adhesion Receptors

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Gianni Francesco Guidetti ◽  
Mauro Torti
Keyword(s):  
Cell Adhesion ◽  
Signaling Pathways ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Small Gtpases ◽  
Small Gtpase ◽  
Complex Pattern ◽  
Adhesive Properties ◽  
Adhesion Receptors ◽  
Inside Out

Integrins and other families of cell adhesion receptors are responsible for platelet adhesion and aggregation, which are essential steps for physiological haemostasis, as well as for the development of thrombosis. The modulation of platelet adhesive properties is the result of a complex pattern of inside-out and outside-in signaling pathways, in which the members of the Rap family of small GTPases are bidirectionally involved. This paper focuses on the regulation of the main Rap GTPase expressed in circulating platelets, Rap1b, downstream of adhesion receptors, and summarizes the most recent achievements in the investigation of the function of this protein as regulator of platelet adhesion and thrombus formation.

scholarly journals ROCK and mDia1 antagonize in Rho-dependent Rac activation in Swiss 3T3 fibroblasts

2002 ◽  
Vol 157 (5) ◽  
pp. 819-830 ◽  
Author(s):  
Takahiro Tsuji ◽  
Toshimasa Ishizaki ◽  
Muneo Okamoto ◽  
Chiharu Higashida ◽  
Kazuhiro Kimura ◽  
...  
Keyword(s):  
Focal Adhesions ◽  
Small Gtpase ◽  
Dominant Negative ◽  
Stress Fibers ◽  
Induced Membrane ◽  
3T3 Fibroblasts ◽  
C3 Exoenzyme ◽  
Swiss 3T3 ◽  
Swiss 3T3 Fibroblasts ◽  
Membrane Ruffle

The small GTPase Rho acts on two effectors, ROCK and mDia1, and induces stress fibers and focal adhesions. However, how ROCK and mDia1 individually regulate signals and dynamics of these structures remains unknown. We stimulated serum-starved Swiss 3T3 fibroblasts with LPA and compared the effects of C3 exoenzyme, a Rho inhibitor, with those of Y-27632, a ROCK inhibitor. Y-27632 treatment suppressed LPA-induced formation of stress fibers and focal adhesions as did C3 exoenzyme but induced membrane ruffles and focal complexes, which were absent in the C3 exoenzyme-treated cells. This phenotype was suppressed by expression of N17Rac. Consistently, the amount of GTP-Rac increased significantly by Y-27632 in LPA-stimulated cells. Biochemically, Y-27632 suppressed tyrosine phosphorylation of paxillin and focal adhesion kinase and not that of Cas. Inhibition of Cas phosphorylation with PP1 or expression of a dominant negative Cas mutant inhibited Y-27632–induced membrane ruffle formation. Moreover, Crk-II mutants lacking in binding to either phosphorylated Cas or DOCK180 suppressed the Y-27632–induced membrane ruffle formation. Finally, expression of a dominant negative mDia1 mutant also inhibited the membrane ruffle formation by Y-27632. Thus, these results have revealed the Rho-dependent Rac activation signaling that is mediated by mDia1 through Cas phosphorylation and antagonized by the action of ROCK.

scholarly journals ArhGAP15, a Rac-specific GTPase-activating Protein, Plays a Dual Role in Inhibiting Small GTPase Signaling

2013 ◽  
Vol 288 (29) ◽  
pp. 21117-21125 ◽  
Author(s):  
Maria Radu ◽  
Sonali J. Rawat ◽  
Alexander Beeser ◽  
Anton Iliuk ◽  
Weiguo Andy Tao ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Protein Microarray ◽  
Small Gtpases ◽  
Dual Role ◽  
Small Gtpase ◽  
Ph Domain ◽  
Gtpase Activating Protein ◽  
Mutual Inhibition ◽  
Negative Role ◽  
Pak Kinase

Signaling from small GTPases is a tightly regulated process. In this work we used a protein microarray screen to identify the Rac-specific GAP, ArhGAP15, as a substrate of the Rac effectors Pak1 and Pak2. In addition to serving as a substrate of Pak1/2, we found that ArhGAP15, via its PH domain, bound to these kinases. The association of ArhGAP15 to Pak1/2 resulted in mutual inhibition of GAP and kinase catalytic activity, respectively. Knock-down of ArhGAP15 resulted in activation of Pak1/2, both indirectly, as a result of Rac activation, and directly, as a result of disruption of the ArhGAP15/Pak complex. Our data suggest that ArhGAP15 plays a dual negative role in regulating small GTPase signaling, by acting at the level of the GTPase itself, as well interacting with its effector, Pak kinase.

scholarly journals PseudoGTPase domains in p190RhoGAP proteins: a mini-review

2018 ◽  
Vol 46 (6) ◽  
pp. 1713-1720 ◽  
Author(s):  
Amy L. Stiegler ◽  
Titus J. Boggon
Keyword(s):  
Family Members ◽  
Small Gtpases ◽  
Small Gtpase ◽  
Signaling Proteins ◽  
New Family ◽  
Gtpase Activating Proteins ◽  
Rho Family ◽  
Biochemical Analyses ◽  
Catalytic Cleft

Pseudoenzymes generally lack detectable catalytic activity despite adopting the overall protein fold of their catalytically competent counterparts, indeed ‘pseudo’ family members seem to be incorporated in all enzyme classes. The small GTPase enzymes are important signaling proteins, and recent studies have identified many new family members with noncanonical residues within the catalytic cleft, termed pseudoGTPases. To illustrate recent discoveries in the field, we use the p190RhoGAP proteins as an example. p190RhoGAP proteins (ARHGAP5 and ARHGAP35) are the most abundant GTPase activating proteins for the Rho family of small GTPases. These are key regulators of Rho signaling in processes such as cell migration, adhesion and cytokinesis. Structural biology has complemented and guided biochemical analyses for these proteins and has allowed discovery of two cryptic pseudoGTPase domains, and the re-classification of a third, previously identified, GTPase-fold domain as a pseudoGTPase. The three domains within p190RhoGAP proteins illustrate the diversity of this rapidly expanding pseudoGTPase group.

scholarly journals Identification and characterization of a new isoform of small GTPase RhoE

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Yuan Dai ◽  
Weijia Luo ◽  
Xiaojing Yue ◽  
Wencai Ma ◽  
Jing Wang ◽  
...  
Keyword(s):  
Rho Gtpase ◽  
Small Gtpases ◽  
Small Gtpase ◽  
Biological Functions ◽  
Coding Region ◽  
Alternative Translation ◽  
Rho Family ◽  
Binding Capability ◽  
Identification And Characterization

Abstract The Rho family of GTPases consists of 20 members including RhoE. Here, we discover the existence of a short isoform of RhoE designated as RhoEα, the first Rho GTPase isoform generated from alternative translation. Translation of this new isoform is initiated from an alternative start site downstream of and in-frame with the coding region of the canonical RhoE. RhoEα exhibits a similar subcellular distribution while its protein stability is higher than RhoE. RhoEα contains binding capability to RhoE effectors ROCK1, p190RhoGAP and Syx. The distinct transcriptomes of cells with the expression of RhoE and RhoEα, respectively, are demonstrated. The data propose distinctive and overlapping biological functions of RhoEα compared to RhoE. In conclusion, this study reveals a new Rho GTPase isoform generated from alternative translation. The discovery provides a new scope of understanding the versatile functions of small GTPases and underlines the complexity and diverse roles of small GTPases.

scholarly journals The Tyrosine Phosphatase hPTPRβ Controls the Early Signals and Dopaminergic Cells Viability via the P2X7 Receptor

2021 ◽  
Vol 22 (23) ◽  
pp. 12936
Author(s):  
Francisco Llavero Bernal ◽  
Miriam Luque Montoro ◽  
Alazne Arrazola Sastre ◽  
Hadriano M. Lacerda ◽  
José Luis Zugaza
Keyword(s):  
Cell Death ◽  
Dopaminergic Neurons ◽  
P2x7 Receptor ◽  
Purinergic Receptors ◽  
Neuronal Response ◽  
Tyrosine Phosphatase ◽  
Neuronal Cell ◽  
Small Gtpases ◽  
Small Gtpase ◽  
Dopaminergic Cells

ATP, one of the signaling molecules most commonly secreted in the nervous system and capable of stimulating multiple pathways, binds to the ionotropic purinergic receptors, in particular, the P2X7 receptor (P2X7R) and stimulates neuronal cell death. Given this effect of purinergic receptors on the viability of dopaminergic neurons model cells and that Ras GTPases control Erk1/2-regulated mitogen-activated cell proliferation and survival, we have investigated the role of the small GTPases of the Ras superfamily, together with their regulatory and effector molecules as the potential molecular intermediates in the P2X7R-regulated cell death of SN4741 dopaminergic neurons model cells. Here, we demonstrate that the neuronal response to purinergic stimulation involves the Calmodulin/RasGRF1 activation of the small GTPase Ras and Erk1/2. We also demonstrate that tyrosine phosphatase PTPRβ and other tyrosine phosphatases regulate the small GTPase activation pathway and neuronal viability. Our work expands the knowledge on the intracellular responses of dopaminergic cells by identifying new participating molecules and signaling pathways. In this sense, the study of the molecular circuitry of these neurons is key to understanding the functional effects of ATP, as well as considering the importance of these cells in Parkinson’s Disease.

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