scholarly journals Localized Rho GTPase Activation Regulates RNA Dynamics and Compartmentalization in Tumor Cell Protrusions

2008 ◽  
Vol 283 (50) ◽  
pp. 34785-34795 ◽  
Author(s):  
Heather C. Stuart ◽  
Zongjian Jia ◽  
Anat Messenberg ◽  
Bharat Joshi ◽  
T. Michael Underhill ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Rho Gtpase ◽  
Rna Dynamics ◽  
Gtpase Activation

scholarly journals A Genome-Wide Screen in Mice To Identify Cell-Extrinsic Regulators of Pulmonary Metastatic Colonisation

2020 ◽  
Vol 10 (6) ◽  
pp. 1869-1877
Author(s):  
Louise van der Weyden ◽  
Agnieszka Swiatkowska ◽  
Vivek Iyer ◽  
Anneliese O. Speak ◽  
David J. Adams
Keyword(s):  
Tumor Cell ◽  
Rho Gtpase ◽  
Metastatic Tumor ◽  
Secondary Site ◽  
Extrinsic Factors ◽  
Metastatic Colonization ◽  
Genotype Effect ◽  
Genome Wide ◽  
A Genome ◽  
Gtpase Activation

Metastatic colonization, whereby a disseminated tumor cell is able to survive and proliferate at a secondary site, involves both tumor cell-intrinsic and -extrinsic factors. To identify tumor cell-extrinsic (microenvironmental) factors that regulate the ability of metastatic tumor cells to effectively colonize a tissue, we performed a genome-wide screen utilizing the experimental metastasis assay on mutant mice. Mutant and wildtype (control) mice were tail vein-dosed with murine metastatic melanoma B16-F10 cells and 10 days later the number of pulmonary metastatic colonies were counted. Of the 1,300 genes/genetic locations (1,344 alleles) assessed in the screen 34 genes were determined to significantly regulate pulmonary metastatic colonization (15 increased and 19 decreased; P < 0.005 and genotype effect <-55 or >+55). While several of these genes have known roles in immune system regulation (Bach2, Cyba, Cybb, Cybc1, Id2, Igh-6, Irf1, Irf7, Ncf1, Ncf2, Ncf4 and Pik3cg) most are involved in a disparate range of biological processes, ranging from ubiquitination (Herc1) to diphthamide synthesis (Dph6) to Rho GTPase-activation (Arhgap30 and Fgd4), with no previous reports of a role in the regulation of metastasis. Thus, we have identified numerous novel regulators of pulmonary metastatic colonization, which may represent potential therapeutic targets.

scholarly journals Chronic lymphocytic leukemia cells induce defective LFA-1–directed T-cell motility by altering Rho GTPase signaling that is reversible with lenalidomide

Blood ◽  
2013 ◽  
Vol 121 (14) ◽  
pp. 2704-2714 ◽  
Author(s):  
Alan G. Ramsay ◽  
Rachel Evans ◽  
Shahryar Kiaii ◽  
Lena Svensson ◽  
Nancy Hogg ◽  
...  
Keyword(s):  
T Cell ◽  
Chronic Lymphocytic Leukemia ◽  
Cell Motility ◽  
Rho Gtpase ◽  
Lymphocytic Leukemia ◽  
Leukemia Cells ◽  
Key Points ◽  
Gtpase Activation ◽  
Activation Signaling

Key Points CLL cells induce defects in T-cell LFA-1–mediated migration by altering Rho GTPase activation signaling, downregulating RhoA and Rac1, and upregulating Cdc42. Lenalidomide repairs these T-cell defects by restoring normal Rho GTPase activation signaling.

scholarly journals Impaired Rho GTPase activation abrogates cell polarization and migration in macrophages with defective lipolysis

2011 ◽  
Vol 68 (23) ◽  
pp. 3933-3947 ◽  
Author(s):  
Elma Aflaki ◽  
Nariman A. B. Balenga ◽  
Petra Luschnig-Schratl ◽  
Heimo Wolinski ◽  
Silvia Povoden ◽  
...  
Keyword(s):  
Rho Gtpase ◽  
Cell Polarization ◽  
Gtpase Activation ◽  
And Migration

scholarly journals Histone deacetylase 6-mediated deacetylation of α-tubulin coordinates cytoskeletal and signaling events during platelet activation

2013 ◽  
Vol 305 (12) ◽  
pp. C1230-C1239 ◽  
Author(s):  
Joseph E. Aslan ◽  
Kevin G. Phillips ◽  
Laura D. Healy ◽  
Asako Itakura ◽  
Jiaqing Pang ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Rho Gtpase ◽  
Specific Inhibitor ◽  
Covalent Modification ◽  
Histone Deacetylase 6 ◽  
Signaling Systems ◽  
Glycoprotein Vi ◽  
Marginal Band ◽  
Signaling Events ◽  
Gtpase Activation

The tubulin cytoskeleton plays a key role in maintaining the characteristic quiescent discoid shape of resting platelets. Upon activation, platelets undergo a dramatic change in shape; however, little is known of how the microtubule system contributes to regulating platelet shape and function. Here we investigated the role of the covalent modification of α-tubulin by acetylation in the regulation of platelet physiology during activation. Superresolution microscopy analysis of the platelet tubulin cytoskeleton showed that the marginal band together with an interconnected web of finer tubulin structures collapsed upon platelet activation with the glycoprotein VI (GPVI)-agonist collagen-related peptide (CRP). Western blot analysis revealed that α-tubulin was acetylated in resting platelets and deacetylated during platelet activation. Tubacin, a specific inhibitor of the tubulin deacetylase HDAC6, prevented tubulin deacetylation upon platelet activation with CRP. Inhibition of HDAC6 upregulated tubulin acetylation and disrupted the organization of the platelet microtubule marginal band without significantly affecting platelet volume changes in response to CRP stimulation. HDAC6 inhibitors also inhibited platelet aggregation in response to CRP and blocked platelet signaling events upstream of platelet Rho GTPase activation. Together, these findings support a role for acetylation signaling in controlling the resting structure of the platelet tubulin marginal band as well as in the coordination of signaling systems that drive platelet cytoskeletal changes and aggregation.

Functional Analysis of Rho GTPase Activation and Inhibition in a Bead-Based Miniaturized Format

2011 ◽  
pp. 271-282 ◽  
Author(s):  
Michael Schmohl ◽  
Stefanie Rimmele ◽  
Peter Gierschik ◽  
Thomas O. Joos ◽  
Nicole Schneiderhan-Marra
Keyword(s):  
Functional Analysis ◽  
Rho Gtpase ◽  
Gtpase Activation

scholarly journals Targeting and activation of Rac1 are mediated by the exchange factor β-Pix

2006 ◽  
Vol 172 (5) ◽  
pp. 759-769 ◽  
Author(s):  
Jean Paul ten Klooster ◽  
Zahara M. Jaffer ◽  
Jonathan Chernoff ◽  
Peter L. Hordijk
Keyword(s):  
Rho Gtpases ◽  
Molecular Mechanisms ◽  
Rho Gtpase ◽  
Focal Adhesions ◽  
Exchange Factor ◽  
Downstream Signaling ◽  
Intracellular Targeting ◽  
Dynamics And Control ◽  
P21 Activated Kinase ◽  
Gtpase Activation

Rho guanosine triphosphatases (GTPases) are critical regulators of cytoskeletal dynamics and control complex functions such as cell adhesion, spreading, migration, and cell division. It is generally accepted that localized GTPase activation is required for the proper initiation of downstream signaling events, although the molecular mechanisms that control targeting of Rho GTPases are unknown. In this study, we show that the Rho GTPase Rac1, via a proline stretch in its COOH terminus, binds directly to the SH3 domain of the Cdc42/Rac activator β-Pix (p21-activated kinase [Pak]–interacting exchange factor). The interaction with β-Pix is nucleotide independent and is necessary and sufficient for Rac1 recruitment to membrane ruffles and to focal adhesions. In addition, the Rac1–β-Pix interaction is required for Rac1 activation by β-Pix as well as for Rac1-mediated spreading. Finally, using cells deficient for the β-Pix–binding kinase Pak1, we show that Pak1 regulates the Rac1–β-Pix interaction and controls cell spreading and adhesion-induced Rac1 activation. These data provide a model for the intracellular targeting and localized activation of Rac1 through its exchange factor β-Pix.

scholarly journals RhoA knockout fibroblasts lose tumor-inhibitory capacity in vitro and promote tumor growth in vivo

2017 ◽  
Vol 114 (8) ◽  
pp. E1413-E1421 ◽  
Author(s):  
Twana Alkasalias ◽  
Andrey Alexeyenko ◽  
Katharina Hennig ◽  
Frida Danielsson ◽  
Robert Jan Lebbink ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Tumor Cell ◽  
Rho Gtpase ◽  
Focal Adhesions ◽  
Cancer Associated Fibroblasts ◽  
Inhibitory Capacity ◽  
Promote Tumor Growth ◽  
Pc3 Cells

Fibroblasts are a main player in the tumor-inhibitory microenvironment. Upon tumor initiation and progression, fibroblasts can lose their tumor-inhibitory capacity and promote tumor growth. The molecular mechanisms that underlie this switch have not been defined completely. Previously, we identified four proteins overexpressed in cancer-associated fibroblasts and linked to Rho GTPase signaling. Here, we show that knocking out the Ras homolog family member A (RhoA) gene in normal fibroblasts decreased their tumor-inhibitory capacity, as judged by neighbor suppression in vitro and accompanied by promotion of tumor growth in vivo. This also induced PC3 cancer cell motility and increased colony size in 2D cultures. RhoA knockout in fibroblasts induced vimentin intermediate filament reorganization, accompanied by reduced contractile force and increased stiffness of cells. There was also loss of wide F-actin stress fibers and large focal adhesions. In addition, we observed a significant loss of α-smooth muscle actin, which indicates a difference between RhoA knockout fibroblasts and classic cancer-associated fibroblasts. In 3D collagen matrix, RhoA knockout reduced fibroblast branching and meshwork formation and resulted in more compactly clustered tumor-cell colonies in coculture with PC3 cells, which might boost tumor stem-like properties. Coculturing RhoA knockout fibroblasts and PC3 cells induced expression of proinflammatory genes in both. Inflammatory mediators may induce tumor cell stemness. Network enrichment analysis of transcriptomic changes, however, revealed that the Rho signaling pathway per se was significantly triggered only after coculturing with tumor cells. Taken together, our findings in vivo and in vitro indicate that Rho signaling governs the inhibitory effects by fibroblasts on tumor-cell growth.

scholarly journals Driving Rho GTPase activity in endothelial cells regulates barrier integrity

2010 ◽  
Vol 103 (01) ◽  
pp. 40-55 ◽  
Author(s):  
Cora Beckers ◽  
Victor van Hinsbergh ◽  
Geerten van Nieuw Amerongen
Keyword(s):  
Barrier Function ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Three Dimensional ◽  
Regulatory Proteins ◽  
Endothelial Barrier ◽  
Endothelial Barrier Function ◽  
Barrier Dysfunction ◽  
Gtpase Activation ◽  
The Individual

SummaryIn the past decade understanding of the role of the Rho GTPases RhoA, Rac1 and Cdc42 has been developed from regulatory proteins that regulate specific actin cytoskeletal structures – stress fibers, lamellipodia and filopodia – to complex integrators of cytoskeletal structures that can exert multiple functions depending on the cellular context. Fundamental to these functions are three-dimensional complexes between the individual Rho GTPases, their specific activators (GEFs) and inhibitors (GDIs and GAPs), which greatly outnumber the Rho GTPases themselves, and additional regulatory proteins. By this complexity of regulation different vasoactive mediators can induce various cytoskeletal structures that enable the endothelial cell (EC) to respond adequately. In this review we have focused on this complexity and the consequences of Rho GTPase regulation for endothelial barrier function. The permeability inducers thrombin and VEGF are presented as examples of G-protein coupled receptor- and tyrosine kinase receptormediated Rho GTPase activation, respectively. These mediators induce complex but markedly different networks of activators, inhibitors and effectors of Rho GTPases, which alter the endothelial barrier function. An interesting feature in this regulation is that Rho GTPases often have both barrier-protecting and barrier-disturbing functions. While Rac1 enforces the endothelial junctions, it becomes part of a barrier-disturbing mechanism as activator of reactive oxygen species generating NADPH oxidase. Similarly RhoA is protective under basal conditions, but becomes involved in barrier dysfunction after activation of ECs by thrombin. The challenge and promise lies in unfolding this complex regulation, as this will provide leads for new therapeutic opportunities.

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