scholarly journals An Elmo–Dock complex locally controls Rho GTPases and actin remodeling during cadherin-mediated adhesion

2014 ◽  
Vol 207 (5) ◽  
pp. 577-587 ◽  
Author(s):  
Christopher P. Toret ◽  
Caitlin Collins ◽  
W. James Nelson
Keyword(s):  
Cell Adhesion ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Cell Contact ◽  
Nucleotide Exchange ◽  
Cell Contacts ◽  
Guanine Nucleotide Exchange ◽  
A Genome ◽  
Dependent Cell ◽  
Cell Cell

Cell–cell contact formation is a dynamic process requiring the coordination of cadherin-based cell–cell adhesion and integrin-based cell migration. A genome-wide RNA interference screen for proteins required specifically for cadherin-dependent cell–cell adhesion identified an Elmo–Dock complex. This was unexpected as Elmo–Dock complexes act downstream of integrin signaling as Rac guanine-nucleotide exchange factors. In this paper, we show that Elmo2 recruits Dock1 to initial cell–cell contacts in Madin–Darby canine kidney cells. At cell–cell contacts, both Elmo2 and Dock1 are essential for the rapid recruitment and spreading of E-cadherin, actin reorganization, localized Rac and Rho GTPase activities, and the development of strong cell–cell adhesion. Upon completion of cell–cell adhesion, Elmo2 and Dock1 no longer localize to cell–cell contacts and are not required subsequently for the maintenance of cell–cell adhesion. These studies show that Elmo–Dock complexes are involved in both integrin- and cadherin-based adhesions, which may help to coordinate the transition of cells from migration to strong cell–cell adhesion.

scholarly journals MAGI-1 Is Required for Rap1 Activation upon Cell-Cell Contact and for Enhancement of Vascular Endothelial Cadherin-mediated Cell Adhesion

2006 ◽  
Vol 17 (2) ◽  
pp. 966-976 ◽  
Author(s):  
Atsuko Sakurai ◽  
Shigetomo Fukuhara ◽  
Akiko Yamagishi ◽  
Keisuke Sako ◽  
Yuji Kamioka ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Adherens Junction ◽  
Small Gtpase ◽  
Cell Contact ◽  
Vascular Endothelial ◽  
Nucleotide Exchange ◽  
Cell Contacts ◽  
Vascular Endothelial Cadherin ◽  
Rap1 Activation ◽  
Cell Cell

Rap1 is a small GTPase that regulates adherens junction maturation. It remains elusive how Rap1 is activated upon cell-cell contact. We demonstrate for the first time that Rap1 is activated upon homophilic engagement of vascular endothelial cadherin (VE-cadherin) at the cell-cell contacts in living cells and that MAGI-1 is required for VE-cadherin-dependent Rap1 activation. We found that MAGI-1 localized to cell-cell contacts presumably by associating with β-catenin and that MAGI-1 bound to a guanine nucleotide exchange factor for Rap1, PDZ-GEF1. Depletion of MAGI-1 suppressed the cell-cell contact-induced Rap1 activation and the VE-cadherin-mediated cell-cell adhesion after Ca2+ switch. In addition, relocation of vinculin from cell-extracellular matrix contacts to cell-cell contacts after the Ca2+ switch was inhibited in MAGI-1-depleted cells. Furthermore, inactivation of Rap1 by overexpression of Rap1GAPII impaired the VE-cadherin-dependent cell adhesion. Collectively, MAGI-1 is important for VE-cadherin-dependent Rap1 activation upon cell-cell contact. In addition, once activated, Rap1 upon cell-cell contacts positively regulate the adherens junction formation by relocating vinculin that supports VE-cadherin-based cell adhesion.

scholarly journals Rap1 Regulates the Formation of E-Cadherin-Based Cell-Cell Contacts

2004 ◽  
Vol 24 (15) ◽  
pp. 6690-6700 ◽  
Author(s):  
Catherine Hogan ◽  
Norberto Serpente ◽  
Patricia Cogram ◽  
Catherine Rose Hosking ◽  
Carl Uli Bialucha ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Vital Role ◽  
Nucleotide Exchange ◽  
Cell Contacts ◽  
Contact Sites ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Cell Adhesion Proteins ◽  
E Cadherin ◽  
Cell Cell

ABSTRACT In epithelial tissues, cells are linked to their neighbors through specialized cell-cell adhesion proteins. E-cadherin is one of the most important membrane proteins for the establishment of intimate cell-cell contacts, but the molecular mechanism by which it is recruited to contact sites is largely unknown. We report here that the cytoplasmic domain of E-cadherin interacts with C3G, a guanine nucleotide exchange factor for Rap1. In epithelial cell cultures, ligation of the extracellular domain of E-cadherin enhances Rap1 activity, which in turn is necessary for the proper targeting of E-cadherin molecules to maturing cell-cell contacts. Furthermore, our data suggest that Cdc42 functions downstream of Rap1 in this process. We conclude that Rap1 plays a vital role in the establishment of E-cadherin-based cell-cell adhesion.

scholarly journals Selectivity of Guanine Nucleotide Exchange Factor-mediated Cdc42 activation in primary human endothelial cells

2019 ◽  
Author(s):  
Nathalie R. Reinhard ◽  
Sanne van der Niet ◽  
Anna Chertkova ◽  
Marten Postma ◽  
Peter L. Hordijk ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Single Cell ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Actin Dynamics ◽  
Pleckstrin Homology Domain ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
Dh Domain

AbstractThe Rho GTPase family is involved in actin dynamics and regulates the barrier function of the endothelium. One of the main barrier-promoting Rho GTPases is Cdc42, also known as cell division control protein 42 homolog. Currently, regulation of Cdc42-based signaling networks in endothelial cells (ECs) lack molecular details. To examine these, we focused on a subset of 15 Rho guanine nucleotide exchange factors (GEFs), which are expressed in the endothelium. By performing single cell FRET measurements with Rho GTPase biosensors in primary human ECs, we monitored GEF efficiency towards Cdc42 and Rac1. A new, single cell-based analysis was developed and used to enable the quantitative comparison of cellular activities of the full-length GEFs. Our data reveal a specific GEF dependent activation profile, with most efficient Cdc42 activation induced by PLEKHG2, FGD1, PLEKHG1 and pRex1 and the highest selectivity for FGD1. Additionally, we generated truncated GEF constructs that comprise only the catalytic dbl homology (DH) domain or together with the adjacent pleckstrin homology domain (DHPH). The DH domain by itself did not activate Cdc42, whereas the DHPH domain of ITSN1, ITSN2 and PLEKHG1 showed activity towards Cdc42. Together, our study characterized endothelial GEFs that may activate Cdc42, which will be of great value for the field of vascular biology.Abstract FigureGraphical Abstract

scholarly journals Hormones Secretion and Rho GTPases in Neuroendocrine Tumors

Cancers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1859
Author(s):  
Laura Streit ◽  
Laurent Brunaud ◽  
Nicolas Vitale ◽  
Stéphane Ory ◽  
Stéphane Gasman
Keyword(s):  
Neuroendocrine Tumors ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Secretory Activity ◽  
Guanine Nucleotide Exchange Factors ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Gtpase Activating Proteins

Neuroendocrine tumors (NETs) belong to a heterogeneous group of neoplasms arising from hormone secreting cells. These tumors are often associated with a dysfunction of their secretory activity. Neuroendocrine secretion occurs through calcium-regulated exocytosis, a process that is tightly controlled by Rho GTPases family members. In this review, we compiled the numerous mutations and modification of expression levels of Rho GTPases or their regulators (Rho guanine nucleotide-exchange factors and Rho GTPase-activating proteins) that have been identified in NETs. We discussed how they might regulate neuroendocrine secretion.

scholarly journals MicroRNA Regulation of the Small Rho GTPase Regulators—Complexities and Opportunities in Targeting Cancer Metastasis

Cancers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1092 ◽  
Author(s):  
Brock A. Humphries ◽  
Zhishan Wang ◽  
Chengfeng Yang
Keyword(s):  
Transcriptional Activation ◽  
Rho Gtpases ◽  
Cancer Metastasis ◽  
Rho Gtpase ◽  
Critical Role ◽  
Large Family ◽  
Actin Dynamics ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange

The small Rho GTPases regulate important cellular processes that affect cancer metastasis, such as cell survival and proliferation, actin dynamics, adhesion, migration, invasion and transcriptional activation. The Rho GTPases function as molecular switches cycling between an active GTP-bound and inactive guanosine diphosphate (GDP)-bound conformation. It is known that Rho GTPase activities are mainly regulated by guanine nucleotide exchange factors (RhoGEFs), GTPase-activating proteins (RhoGAPs), GDP dissociation inhibitors (RhoGDIs) and guanine nucleotide exchange modifiers (GEMs). These Rho GTPase regulators are often dysregulated in cancer; however, the underlying mechanisms are not well understood. MicroRNAs (miRNAs), a large family of small non-coding RNAs that negatively regulate protein-coding gene expression, have been shown to play important roles in cancer metastasis. Recent studies showed that miRNAs are capable of directly targeting RhoGAPs, RhoGEFs, and RhoGDIs, and regulate the activities of Rho GTPases. This not only provides new evidence for the critical role of miRNA dysregulation in cancer metastasis, it also reveals novel mechanisms for Rho GTPase regulation. This review summarizes recent exciting findings showing that miRNAs play important roles in regulating Rho GTPase regulators (RhoGEFs, RhoGAPs, RhoGDIs), thus affecting Rho GTPase activities and cancer metastasis. The potential opportunities and challenges for targeting miRNAs and Rho GTPase regulators in treating cancer metastasis are also discussed. A comprehensive list of the currently validated miRNA-targeting of small Rho GTPase regulators is presented as a reference resource.

scholarly journals N-Cadherin Association with Lipid Rafts Regulates Its Dynamic Assembly at Cell-Cell Junctions in C2C12 Myoblasts

2005 ◽  
Vol 16 (5) ◽  
pp. 2168-2180 ◽  
Author(s):  
Marie Causeret ◽  
Nicolas Taulet ◽  
Franck Comunale ◽  
Cyril Favard ◽  
Cécile Gauthier-Rouvière
Keyword(s):  
Plasma Membrane ◽  
Cell Adhesion ◽  
Lipid Rafts ◽  
Membrane Lipid ◽  
Cell Junctions ◽  
Cell Contact ◽  
C2c12 Myoblasts ◽  
Cell Contacts ◽  
Dynamic Assembly ◽  
Cell Cell

Cadherins are homophilic cell-cell adhesion molecules implicated in cell growth, differentiation, and organization into tissues during embryonic development. They accumulate at cell-cell contact sites and act as adhesion-activated signaling receptors. Here, we show that the dynamic assembly of N-cadherin at cell-cell contacts involves lipid rafts. In C2C12 myoblasts, immunofluorescence and biochemical experiments demonstrate that N-cadherin present at cell-cell contacts is colocalized with lipid rafts. Disruption of lipid rafts leads to the inhibition of cell-cell adhesion and disorganization of N-cadherin–dependent cell-cell contacts without modifying the association of N-cadherin with catenins and its availability at the plasma membrane. Fluorescent recovery after photobleaching experiments demonstrate that at the dorsal plasma membrane, lipid rafts are not directly involved in the diffusional mobility of N-cadherin. In contrast, at cell-cell junctions N-cadherin association with lipid rafts allows its stabilization enabling the formation of a functional adhesive complex. We show that lipid rafts, as homophilic interaction and F-actin association, stabilize cadherin-dependent adhesive complexes. Homophilic interactions and F-actin association of N-cadherin are both required for its association to lipid rafts. We thus identify lipid rafts as new regulators of cadherin-mediated cell adhesion.

scholarly journals The dynamics of spatio-temporal Rho GTPase signaling: formation of signaling patterns

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 749 ◽  
Author(s):  
Rafael Dominik Fritz ◽  
Olivier Pertz
Keyword(s):  
Rho Gtpases ◽  
Rho Gtpase ◽  
Activity Patterns ◽  
Gtpase Activity ◽  
Nucleotide Exchange ◽  
Novel Technologies ◽  
Temporal Complexity ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Spatio Temporal

Rho GTPases are crucial signaling molecules that regulate a plethora of biological functions. Traditional biochemical, cell biological, and genetic approaches have founded the basis of Rho GTPase biology. The development of biosensors then allowed measuring Rho GTPase activity with unprecedented spatio-temporal resolution. This revealed that Rho GTPase activity fluctuates on time and length scales of tens of seconds and micrometers, respectively. In this review, we describe Rho GTPase activity patterns observed in different cell systems. We then discuss the growing body of evidence that upstream regulators such as guanine nucleotide exchange factors and GTPase-activating proteins shape these patterns by precisely controlling the spatio-temporal flux of Rho GTPase activity. Finally, we comment on additional mechanisms that might feed into the regulation of these signaling patterns and on novel technologies required to dissect this spatio-temporal complexity.

scholarly journals Distinct Rho GTPase Activities Regulate Epithelial Cell Localization of the Adhesion Molecule CEACAM1: Involvement of the CEACAM1 Transmembrane Domain

2003 ◽  
Vol 23 (20) ◽  
pp. 7291-7304 ◽  
Author(s):  
Bénédicte Fournès ◽  
Jennifer Farrah ◽  
Melanie Olson ◽  
Nathalie Lamarche-Vane ◽  
Nicole Beauchemin
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Transmembrane Domain ◽  
Rho Kinase ◽  
Cell Contacts ◽  
Cell Localization ◽  
Downstream Effector ◽  
Cell Cell

ABSTRACT CEACAM1 is an intercellular adhesion glycoprotein. As CEACAM1 plays an important role in epithelial cell signaling and functions, we have examined its localization in epithelial cells. We have observed that distribution at cell contacts is not always seen in these cells, suggesting that CEACAM1 localization might be regulated. In Swiss 3T3 cells, the targeting of CEACAM1 at cell-cell boundaries is regulated by the Rho GTPases. In the present study, we have used the MDCK epithelial cells to characterize the effects of the Rho GTPases and their effectors on CEACAM1 intercellular targeting. Activated Cdc42 and Rac1 or their downstream effector PAK1 targeted CEACAM1 to sites of cell-cell contacts. On the other hand, neither activated RhoA nor activated Rho kinase directed CEACAM1 to cell boundaries, resulting in a condensed distribution of CEACAM1 at the cell surface. Interestingly, inhibition of this pathway resulted in CEACAM1 intercellular localization suggesting that a tightly regulated balance of Rho GTPase activities is necessary to target CEACAM1 at cell-cell boundaries. In addition, using CEACAM1 mutants and chimeric fusion constructs containing domains of the colony-stimulating factor receptor, we have shown that the transmembrane domain of CEACAM1 is responsible for the Cdc42-induced targeting at cell-cell contacts.

scholarly journals Vascular Endothelial-Cadherin Stabilizes at Cell–Cell Junctions by Anchoring to Circumferential Actin Bundles through α- and β-Catenins in Cyclic AMP-Epac-Rap1 Signal-activated Endothelial Cells

2010 ◽  
Vol 21 (4) ◽  
pp. 584-596 ◽  
Author(s):  
Kazuomi Noda ◽  
Jianghui Zhang ◽  
Shigetomo Fukuhara ◽  
Satoshi Kunimoto ◽  
Michihiro Yoshimura ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Classical Model ◽  
Green Fluorescence Protein ◽  
Cell Junctions ◽  
Vascular Endothelial ◽  
Cell Contacts ◽  
Actin Bundles ◽  
Dependent Cell ◽  
A Cell ◽  
Cell Cell

Vascular endothelial (VE)-cadherin is a cell–cell adhesion molecule involved in endothelial barrier functions. Previously, we reported that cAMP-Epac-Rap1 signal enhances VE-cadherin–dependent cell adhesion. Here, we further scrutinized how cAMP-Epac-Rap1 pathway promotes stabilization of VE-cadherin at the cell–cell contacts. Forskolin induced circumferential actin bundling and accumulation of VE-cadherin fused with green fluorescence protein (VEC-GFP) on the bundled actin filaments. Fluorescence recovery after photobleaching (FRAP) analyses using VEC-GFP revealed that forskolin stabilizes VE-cadherin at cell–cell contacts. These effects of forskolin were mimicked by an activator for Epac but not by that for protein kinase A. Forskolin-induced both accumulation and stabilization of junctional VEC-GFP was impeded by latrunculin A. VE-cadherin, α-catenin, and β-catenin were dispensable for forskolin-induced circumferential actin bundling, indicating that homophilic VE-cadherin association is not the trigger of actin bundling. Requirement of α- and β-catenins for forskolin-induced stabilization of VE-cadherin on the actin bundles was confirmed by FRAP analyses using VEC-GFP mutants, supporting the classical model that α-catenin could potentially link the bundled actin to cadherin. Collectively, circumferential actin bundle formation and subsequent linkage between actin bundles and VE-cadherin through α- and β-catenins are important for the stabilization of VE-cadherin at the cell–cell contacts in cAMP-Epac-Rap1 signal-activated cells.

The role of Rap1 in integrin-mediated cell adhesion

2003 ◽  
Vol 31 (1) ◽  
pp. 83-86 ◽  
Author(s):  
J.L. Bos ◽  
K. de Bruyn ◽  
J. Enserink ◽  
B. Kuiperij ◽  
S. Rangarajan ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Second Messengers ◽  
Small Gtpases ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Downstream Effectors ◽  
Extracellular Signal ◽  
A Genome ◽  
Inside Out

Rap1 is a member of the Ras-like small GTPases. Originally the protein was identified in a genome-wide screen for suppressors of Ras transformation, but the mechanism of this reversion remained elusive. We have investigated the signalling function of Rap1. We observed that Rap1 is activated by a large variety of stimuli, including growth factors, neurotransmitters and cytokines. Common second messengers like cAMP, diacylglycerol and calcium are mediators of this activation. These messengers activate guanine nucleotide exchange factors (GEFs), the most notable of which is Epac (exchange protein directly activated by cAMP). However, the downstream effectors of Rap1 are less clear. Although direct connections of Rap1 with the serine/threonine kinases Raf1 and B-raf have been reported, we were unable to find functional evidence for an interaction of endogenous Rap1 signalling with the Raf/extracellular-signal-regulated kinase (ERK) pathway. Instead we observe a clear connection of Rap1 with inside-out signalling to integrins. Indeed, introduction of a constitutively active Rap1 as well as Epac induces integrin-mediated cell adhesion, whereas inhibition of Rap1 signalling by the introduction of Rap1GAP (GTPase-activating protein) inhibits inside-out activation of integrins. More importantly, activation of a Gs-protein-coupled receptor results in integrin-mediated cell adhesion, by a pathway involving Epac and Rap1. From these results, we conclude that one of the functions of receptor-induced Rap1 activation is inside-out regulation of integrins.

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