scholarly journals Arp2/3-Branched Actin Maintains an Active Pool of GTP-RhoA and Controls RhoA Abundance

Cells ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1264
Author(s):  
Yuxing Huang ◽  
Xin Yi ◽  
Chenlu Kang ◽  
Congying Wu
Keyword(s):  
Signal Transduction ◽  
Cell Motility ◽  
Small Gtpases ◽  
Small Gtpase ◽  
Protein Abundance ◽  
Rhoa Activity ◽  
Cytoskeletal Dynamics ◽  
Active Pool ◽  
Spatiotemporal Control

Small GTPases regulate cytoskeletal dynamics, cell motility, and division under precise spatiotemporal control. Different small GTPases exhibit cross talks to exert feedback response or to act in concert during signal transduction. However, whether and how specific cytoskeletal components’ feedback to upstream signaling factors remains largely elusive. Here, we report an intriguing finding that disruption of the Arp2/3-branched actin specifically reduces RhoA activity but upregulates its total protein abundance. We further dissect the mechanisms underlying these circumstances and identify the altered cortactin/p190RhoGAP interaction and weakened CCM2/Smurf1 binding to be involved in GTP-RhoA reduction and total RhoA increase, respectively. Moreover, we find that cytokinesis defects induced by Arp2/3 inhibition can be rescued by activating RhoA. Our study reveals an intricate feedback from the actin cytoskeleton to the small GTPase. Our work highlights the role of Arp2/3-branched actin in signal transduction aside from its function in serving as critical cytoskeletal components to maintain cell morphology and motility.

Protein–membrane interactions in small GTPase signalling and pharmacology: perspectives from Arf GTPases studies

2020 ◽  
Vol 48 (6) ◽  
pp. 2721-2728
Author(s):  
Agata Nawrotek ◽  
Mahel Zeghouf ◽  
Jacqueline Cherfils
Keyword(s):  
Signal Transduction ◽  
Membrane Trafficking ◽  
Biochemical Properties ◽  
Small Gtpases ◽  
Small Gtpase ◽  
Cardiac Diseases ◽  
Membrane Interactions ◽  
Protein Membrane ◽  
Cytoskeletal Dynamics ◽  
Arf Gtpases

Small GTPases, in association with their GEFs, GAPs and effectors, control major intracellular processes such as signal transduction, cytoskeletal dynamics and membrane trafficking. Accordingly, dysfunctions in their biochemical properties are associated with many diseases, including cancers, diabetes, infections, mental disorders and cardiac diseases, which makes them attractive targets for therapies. However, small GTPases signalling modules are not well-suited for classical inhibition strategies due to their mode of action that combines protein–protein and protein–membrane interactions. As a consequence, there is still no validated drug available on the market that target small GTPases, whether directly or through their regulators. Alternative inhibitory strategies are thus highly needed. Here we review recent studies that highlight the unique modalities of the interaction of small GTPases and their GEFs at the periphery of membranes, and discuss how they can be harnessed in drug discovery.

scholarly journals Specific Phosphorylation of p120-Catenin Regulatory Domain Differently Modulates Its Binding to RhoA

2006 ◽  
Vol 27 (5) ◽  
pp. 1745-1757 ◽  
Author(s):  
Julio Castaño ◽  
Guiomar Solanas ◽  
David Casagolda ◽  
Imma Raurell ◽  
Patricia Villagrasa ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Regulatory Mechanism ◽  
Adherens Junction ◽  
Small Gtpase ◽  
Regulatory Domain ◽  
P120 Catenin ◽  
Tyrosine Residues ◽  
Rhoa Activity ◽  
Intracellular Proteins

ABSTRACT p120-catenin is an adherens junction-associated protein that controls E-cadherin function and stability. p120-catenin also binds intracellular proteins, such as the small GTPase RhoA. In this paper, we identify the p120-catenin N-terminal regulatory domain as the docking site for RhoA. Moreover, we demonstrate that the binding of RhoA to p120-catenin is tightly controlled by the Src family-dependent phosphorylation of p120-catenin on tyrosine residues. The phosphorylation induced by Src and Fyn tyrosine kinases on p120-catenin induces opposite effects on RhoA binding. Fyn, by phosphorylating a residue located in the regulatory domain of p120-catenin (Tyr112), inhibits the interaction of this protein with RhoA. By contrast, the phosphorylation of Tyr217 and Tyr228 by Src promotes a better affinity of p120-catenin towards RhoA. In agreement with these biochemical data, results obtained in cell lines support the important role of these phosphorylation sites in the regulation of RhoA activity by p120-catenin. Taken together, these observations uncover a new regulatory mechanism acting on p120-catenin that contributes to the fine-tuned regulation of the RhoA pathways during specific signaling events.

scholarly journals The role of small GTPases of the Rho/Rac family in TGF-β-induced EMT and cell motility in cancer

2017 ◽  
Vol 247 (3) ◽  
pp. 451-461 ◽  
Author(s):  
Hendrik Ungefroren ◽  
David Witte ◽  
Hendrik Lehnert
Keyword(s):  
Cell Motility ◽  
Small Gtpases

scholarly journals p120 catenin is essential for mesenchymal cadherin–mediated regulation of cell motility and invasiveness

2006 ◽  
Vol 174 (7) ◽  
pp. 1087-1096 ◽  
Author(s):  
Masahiro Yanagisawa ◽  
Panos Z. Anastasiadis
Keyword(s):  
Cell Migration ◽  
Cell Motility ◽  
Tumor Progression ◽  
Cellular Phenotype ◽  
Epithelial Tumor ◽  
P120 Catenin ◽  
Rhoa Activity ◽  
Inappropriate Expression ◽  
E Cadherin

During epithelial tumor progression, the loss of E-cadherin expression and inappropriate expression of mesenchymal cadherins coincide with increased invasiveness. Reexpression experiments have established E-cadherin as an invasion suppressor. However, the mechanism by which E-cadherin suppresses invasiveness and the role of mesenchymal cadherins are poorly understood. We show that both p120 catenin and mesenchymal cadherins are required for the invasiveness of E-cadherin–deficient cells. p120 binding promotes the up-regulation of mesenchymal cadherins and the activation of Rac1, which are essential for cell migration and invasiveness. p120 also promotes invasiveness by inhibiting RhoA activity, independently of cadherin association. Furthermore, association of endogenous p120 with E-cadherin is required for E-cadherin–mediated suppression of invasiveness and is accompanied by a reduction in mesenchymal cadherin levels. The data indicate that p120 acts as a rheostat, promoting a sessile cellular phenotype when associated with E-cadherin or a motile phenotype when associated with mesenchymal cadherins.

DOCK180 Is Induced with Differentiation from CD14 Positive Monocytes and It Regulates Phagocytosis in Both Macrophages and Dendritic Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3077-3077
Author(s):  
Katsuya Fujimoto ◽  
Mitsufumi Nishio ◽  
Hiroshi Nishihara ◽  
Ikumi Sato ◽  
Lei Wang ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Cell Motility ◽  
Western Blotting ◽  
Time Course ◽  
Hematopoietic Cells ◽  
Biological Significance ◽  
Small Gtpase ◽  
Family Protein ◽  
Phagocyte Activity

Abstract A guanine nucleoside exchange factor (GEF), DOCK180, which is an archetype of the CDM family protein, plays a pivotal role in the regulation of cell motility and phagocytosis through the activation of small GTPase Rac. The expression of DOCK180 is mostly ubiquitous except in hematopoietic cells, while another CDM family protein, DOCK2 is strictly found in hematopoietic cells. Although a knockout study against DOCK2 demonstrated the essential role of DOCK2 regarding rodent T- and B-cell motility and chemotaxisis, no involvement of DOCK2 in the action of phagocytes, such as macrophages or dendritic cells (DCs), has yet been observed. We, therefore, investigated the possible role of DOCK180 in the phagocytosis of hematopoietic cells. CD14 positive monocytes, as well as T- or B lymphocytes, isolated from healthy human donors did not express DOCK180 observed by Western blotting. Consistent with this finding, a real time PCR study revealed near negligible levels of DOCK180 mRNA in monocytes. On the other hand, macrophages or DCs, differentiated from monocytes in vitro in the presence of M-CSF or IL-4 and GM-CSF for seven days, were found to express extremely high levels of DOCK180 protein and mRNA. Time course studies showed that DOCK180 mRNA rapidly increased by 6 hours after the induction of CD14 positive monocytes into both macrophages and DCs and its protein expression was clearly detected by Western blotting after Day 2. While the expression of DOCK180 on DCs gradually increased until it reached a plateu level on Day 4, the expression of macrophages showed a linear increase up to Day 7. In contrast to DOCK180, the expression of DOCK2 remained unchanged throughout this study. Furthermore, a phagocytosis assay using Zymosan A particles demonstrated an increase in the phagocyte activity accompanying the expression levels of DOCK180 during both types of differentiation. Protein knockdown assays against DOCK180 using siRNA also confirmed the significance of DOCK180 in the phagocytosis of differentiated macrophages and DCs. Finally, an immunohistochemical study with anti-DOCK180 monoclonal antibody showed that macrophages exhibit the phagocytosis in the front edge of inflammatory granulation tissue, and expressed a high level of DOCK180. Taken together, DOCK180 was thus found to play a role in the induction of phagocyte activity regarding the differentiation from monocytes into either macrophages or DCs, thereby demonstrating the biological significance of DOCK180 in the phagocytosis of human hematopoietic cells.

Control of neutrophil pseudopods by fluid shear: role of Rho family GTPases

2005 ◽  
Vol 288 (4) ◽  
pp. C863-C871 ◽  
Author(s):  
Ayako Makino ◽  
Michael Glogauer ◽  
Gary M. Bokoch ◽  
Shu Chien ◽  
Geert W. Schmid-Schönbein
Keyword(s):  
Signal Transduction ◽  
Shear Stress ◽  
Fluid Shear Stress ◽  
Small Gtpases ◽  
Dependent Manner ◽  
Fluid Shear ◽  
Rho Family

Blood vessels and blood cells are under continuous fluid shear. Studies on vascular endothelium and smooth muscle cells have shown the importance of this mechanical stress in cell signal transduction, gene expression, vascular remodeling, and cell survival. However, in circulating leukocytes, shear-induced signal transduction has not been investigated. Here we examine in vivo and in vitro the control of pseudopods in leukocytes under the influence of fluid shear stress and the role of the Rho family small GTPases. We used a combination of HL-60 cells differentiated into neutrophils (1.4% dimethyl sulfoxide for 5 days) and fresh leukocytes from Rac knockout mice. The cells responded to shear stress (5 dyn/cm2) with retraction of pseudopods and reduction of their projected cell area. The Rac1 and Rac2 activities were decreased by fluid shear in a time- and magnitude-dependent manner, whereas the Cdc42 activity remained unchanged (up to 5 dyn/cm2). The Rho activity was transiently increased and recovered to static levels after 10 min of shear exposure (5 dyn/cm2). Inhibition of either Rac1 or Rac2 slightly but significantly diminished the fluid shear response. Transfection with Rac1-positive mutant enhanced the pseudopod formation during shear. Leukocytes from Rac1-null and Rac2-null mice had an ability to form pseudopods in response to platelet-activating factor but did not respond to fluid shear in vitro. Leukocytes in wild-type mice retracted pseudopods after physiological shear exposure, whereas cells in Rac1-null mice showed no retraction during equal shear. On leukocytes from Rac2-null mice, however, fluid shear exerted a biphasic effect. Leukocytes with extended pseudopods slightly decreased in length, whereas initially round cells increased in length after shear application. The disruption of Rac activity made leukocytes nonresponsive to fluid shear, induced cell adhesion and microvascular stasis, and decreased microvascular density. These results suggest that deactivation of Rac activity by fluid shear plays an important role in stable circulation of leukocytes.

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.

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