Polarized trafficking of E-cadherin is regulated by Rac1 and Cdc42 in Madin-Darby canine kidney cells

2005 ◽  
Vol 288 (6) ◽  
pp. C1411-C1419 ◽  
Author(s):  
Bo Wang ◽  
Fiona G. Wylie ◽  
Rohan D. Teasdale ◽  
Jennifer L. Stow
Keyword(s):  
Cell Surface ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Dominant Negative ◽  
Adhesion Protein ◽  
Cell Functions ◽  
Golgi Transport ◽  
Polarized Trafficking ◽  
Basolateral Trafficking ◽  
E Cadherin

E-cadherin is a major cell-cell adhesion protein of epithelia that is trafficked to the basolateral cell surface in a polarized fashion. The exact post-Golgi route and regulation of E-cadherin transport have not been fully described. The Rho GTPases Cdc42 and Rac1 have been implicated in many cell functions, including the exocytic trafficking of other proteins in polarized epithelial cells. These Rho family proteins are also associated with the cadherin-catenin complexes at the cell surface. We have used functional mutants of Rac1 and Cdc42 and inactivating toxins to demonstrate specific roles for both Cdc42 and Rac1 in the post-Golgi transport of E-cadherin. Dominant-negative mutants of Cdc42 and Rac1 accumulate E-cadherin at a distinct post-Golgi step. This accumulation occurs before p120 ctn interacts with E-cadherin, because p120 ctn localization was not affected by the Cdc42 or Rac1 mutants. Moreover, the GTPase mutants had no effect on the trafficking of a targeting mutant of E-cadherin, consistent with the selective involvement of Cdc42 and Rac1 in basolateral trafficking. These results provide a new example of Rho GTPase regulation of basolateral trafficking and demonstrate novel roles for Cdc42 and Rac1 in the post-Golgi transport of E-cadherin.

Inhibition of RhoA GTPase activity enhances hematopoietic stem and progenitor cell proliferation and engraftment

Blood ◽  
2006 ◽  
Vol 108 (6) ◽  
pp. 2087-2094 ◽  
Author(s):  
Gabriel Ghiaur ◽  
Andrew Lee ◽  
Jeff Bailey ◽  
Jose A. Cancelas ◽  
Yi Zheng ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Progenitor Cells ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Dominant Negative ◽  
Hematopoietic Progenitor Cells ◽  
Hematopoietic Progenitor ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Rhoa Activity

AbstractRas-related Rho GTPases regulate actin cytoskeletal organization, adhesion, gene transcription, and cell-cycle progression. The Rac subfamily of Rho GTPases and Cdc42 has been shown to play essential roles in hematopoietic stem cell (HSC) engraftment and mobilization. Here, we study the role of RhoA, a related Rho GTPase, in HSC functions. Using retrovirus-mediated gene transfer of a dominant-negative (DN) mutant of RhoA (RhoAN19), we demonstrate that down-regulation of RhoA activity resulted in increased HSC engraftment and self-renewal as measured by competitive repopulation and serial transplantation assays. However, overexpression of RhoAN19 resulted in decreased migration toward SDF-1α and α4β1- and α5β2-integrin–mediated adhesion of hematopoietic progenitor cells in vitro. Low RhoA activity was associated with higher proliferation rate of hematopoietic progenitor cells and increased cells in active phases of cell cycle, most likely via decreasing p21Cip/Waf expression and increasing cyclin D1 levels. Thus, reducing RhoA activity by optimizing the balance between adhesion/migration and proliferation/self-renewal results in a net increase in HSC engraftment. This mechanism could provide a novel therapeutic target to enhance HSC therapies.

scholarly journals Fission Yeast Rho5p GTPase Is a Functional Paralogue of Rho1p That Plays a Role in Survival of Spores and Stationary-Phase Cells

2006 ◽  
Vol 5 (3) ◽  
pp. 435-446 ◽  
Author(s):  
Sergio A. Rincón ◽  
Beatriz Santos ◽  
Pilar Pérez
Keyword(s):  
Cell Wall ◽  
Stationary Phase ◽  
Fission Yeast ◽  
Rho Gtpase ◽  
Eukaryotic Cell ◽  
Dominant Negative ◽  
Lytic Enzymes ◽  
Morphological Effect ◽  
Actin Organization ◽  
Cell Functions

ABSTRACT The Rho GTPase family and their effectors are key regulators involved in many eukaryotic cell functions related to actin organization and polarity establishment. Schizosaccharomyces pombe Rho1p is essential, directly activates the (1,3)-β-d-glucan synthase, and participates in regulation of cell wall growth and morphogenesis. Here we describe the characterization of the fission yeast Rho5p GTPase, highly homologous to Rho1p, sharing 86% identity and 95% similarity. Overexpression of the hyperactive allele rho5-G15V causes a morphological effect similar to that of rho1-G15V, but the penetrance is significantly lower, and overexpression of the dominant-negative allele rho5-T20N causes lysis like that of rho1-T20N. Importantly, overexpression of rho5 + but no other rho genes is able to rescue the lethality of rho1Δ cells. Shutoff experiments indicated that Rho5p can replace Rho1p, but it is not as effective in maintaining cell wall integrity or actin organization. rho5 + expression is hardly detected during log-phase growth but is induced under nutritional starvation conditions. rho5Δ cells are viable and do not display any defects during logarithmic growth. However, when rho1 + expression is repressed during stationary phase, rho5Δ cells display reduced viability. Ascospores lacking Rho5p are less resistant to heat or lytic enzymes than wild-type spores. Moreover, h90 mutant strains carrying the hyperactive rho5-G15V or the dominant-negative rho5-T20N alleles display severe ascospore formation defects. These results suggest that Rho5p functions in a way similar to, but less efficient than, Rho1p, plays a nonessential role during stationary phase, and participates in the spore wall formation.

scholarly journals Rho GTPase function in flies: insights from a developmental and organismal perspective

2004 ◽  
Vol 82 (6) ◽  
pp. 643-657 ◽  
Author(s):  
James E Johndrow ◽  
Craig R Magie ◽  
Susan M Parkhurst
Keyword(s):  
Rho Gtpases ◽  
Rho Gtpase ◽  
Fruit Fly ◽  
Genetic System ◽  
Small Gtpases ◽  
Dominant Negative ◽  
Loss Of Function ◽  
Cellular Behavior ◽  
Essential Components ◽  
Work Done

Morphogenesis is a key event in the development of a multicellular organism and is reliant on coordinated transcriptional and signal transduction events. To establish the segmented body plan that underlies much of metazoan development, individual cells and groups of cells must respond to exogenous signals with complex movements and shape changes. One class of proteins that plays a pivotal role in the interpretation of extracellular cues into cellular behavior is the Rho family of small GTPases. These molecular switches are essential components of a growing number of signaling pathways, many of which regulate actin cytoskeletal remodeling. Much of our understanding of Rho biology has come from work done in cell culture. More recently, the fruit fly Drosophila melanogaster has emerged as an excellent genetic system for the study of these proteins in a developmental and organismal context. Studies in flies have greatly enhanced our understanding of pathways involving Rho GTPases and their roles in development.Key words: Rho GTPases, Drosophila, development, effectors, loss-of-function mutation, dominant-negative, constitutively active.

scholarly journals Statins Inhibit HIV-1 Infection by Down-regulating Rho Activity

2004 ◽  
Vol 200 (4) ◽  
pp. 541-547 ◽  
Author(s):  
Gustavo del Real ◽  
Sonia Jiménez-Baranda ◽  
Emilia Mira ◽  
Rosa Ana Lacalle ◽  
Pilar Lucas ◽  
...  
Keyword(s):  
Viral Entry ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Acute Infection ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Target Cells ◽  
Cell Infection ◽  
Cell Counts ◽  
Hiv 1

Human immunodeficiency virus (HIV)-1 infectivity requires actin-dependent clustering of host lipid raft–associated receptors, a process that might be linked to Rho guanosine triphosphatase (GTPase) activation. Rho GTPase activity can be negatively regulated by statins, a family of drugs used to treat hypercholesterolemia in man. Statins mediate inhibition of Rho GTPases by impeding prenylation of small G proteins through blockade of 3-hydroxy-3-methylglutaryl coenzyme A reductase. We show that statins decreased viral load and increased CD4+ cell counts in acute infection models and in chronically HIV-1–infected patients. Viral entry and exit was reduced in statin-treated cells, and inhibition was blocked by the addition of l-mevalonate or of geranylgeranylpyrophosphate, but not by cholesterol. Cell treatment with a geranylgeranyl transferase inhibitor, but not a farnesyl transferase inhibitor, specifically inhibited entry of HIV-1–pseudotyped viruses. Statins blocked Rho-A activation induced by HIV-1 binding to target cells, and expression of the dominant negative mutant RhoN19 inhibited HIV-1 envelope fusion with target cell membranes, reducing cell infection rates. We suggest that statins have direct anti–HIV-1 effects by targeting Rho.

scholarly journals Rho GTPase regulation of exocytosis in yeast is independent of GTP hydrolysis and polarization of the exocyst complex

2005 ◽  
Vol 170 (4) ◽  
pp. 583-594 ◽  
Author(s):  
Olivier Roumanie ◽  
Hao Wu ◽  
Jeffrey N. Molk ◽  
Guendalina Rossi ◽  
Kerry Bloom ◽  
...  
Keyword(s):  
Cell Surface ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Eukaryotic Cells ◽  
Secretory Vesicles ◽  
Polarized Growth ◽  
Gtp Hydrolysis ◽  
Exocyst Complex ◽  
Polarized Exocytosis

Rho GTPases are important regulators of polarity in eukaryotic cells. In yeast they are involved in regulating the docking and fusion of secretory vesicles with the cell surface. Our analysis of a Rho3 mutant that is unable to interact with the Exo70 subunit of the exocyst reveals a normal polarization of the exocyst complex as well as other polarity markers. We also find that there is no redundancy between the Rho3–Exo70 and Rho1–Sec3 pathways in the localization of the exocyst. This suggests that Rho3 and Cdc42 act to polarize exocytosis by activating the exocytic machinery at the membrane without the need to first recruit it to sites of polarized growth. Consistent with this model, we find that the ability of Rho3 and Cdc42 to hydrolyze GTP is not required for their role in secretion. Moreover, our analysis of the Sec3 subunit of the exocyst suggests that polarization of the exocyst may be a consequence rather than a cause of polarized exocytosis.

scholarly journals Role of Rho-GTPases in complement-mediated glomerular epithelial cell injury

2007 ◽  
Vol 293 (1) ◽  
pp. F148-F156 ◽  
Author(s):  
Hui Zhang ◽  
Andrey V. Cybulsky ◽  
Lamine Aoudjit ◽  
Jianxin Zhu ◽  
Hongping Li ◽  
...  
Keyword(s):  
Rho Gtpases ◽  
Cell Injury ◽  
Rho Gtpase ◽  
Morphological Changes ◽  
Small Gtpases ◽  
Dominant Negative ◽  
Glomerular Epithelial Cell ◽  
Rhoa Activity ◽  
Process Formation

Visceral glomerular epithelial cells (GEC) are essential for maintenance of normal glomerular permselectivity. The actin cytoskeleton is a key determinant of GEC morphology and function. In the rat passive Heymann nephritis (PHN) model of membranous nephropathy, complement C5b-9 induces nonlytic GEC injury associated with morphological changes of GEC and proteinuria. The current study addresses the role of Rho family of small GTPases in complement-mediated GEC injury. When cultured rat GEC were stimulated with complement C5b-9 for 18 h, RhoA activity increased, whereas Rac1/Cdc42 activities decreased, compared with control cells. Similar changes in Rho-GTPase activities were observed in glomeruli from rats with PHN. The amount of active p190RhoGAP, a negative upstream regulator of RhoA, was decreased in complement-stimulated GEC, potentially contributing to increased RhoA activity. To address the functional effects of Rho-GTPases, GEC were transfected with constitutively active (CA) or dominant negative (DN) Rho-GTPase mutants. GEC transfected with CA-RhoA showed a smaller and round contour and prominent cortical F-actin. In contrast, GEC transfected with CA-Rac1 demonstrated morphological changes that resembled process formation. In addition, expression of CA-RhoA attenuated complement-mediated cytotoxicity, whereas cytotoxicity was augmented by DN-RhoA. Thus exposure of GEC to complement alters the balance of RhoA, Rac1, and Cdc42 activities. The activity of Rac1 may contribute to process formation, while activation of RhoA (e.g., in the setting of complement attack), with or without blunting of Rac1 activity, may have an opposite effect, i.e., contribute to foot process effacement. Activation of RhoA increases the resistance of GEC to complement-mediated injury.

scholarly journals Regulation of Rho GTPases by RhoGDIs in Human Cancers

Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1037 ◽  
Author(s):  
Cho ◽  
Kim ◽  
Baek ◽  
Kim ◽  
Lee
Keyword(s):  
Cell Migration ◽  
Cancer Progression ◽  
Anticancer Agents ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Regulatory Mechanisms ◽  
Malignant Phenotype ◽  
Cellular Processes ◽  
Human Cancers

Rho GDP dissociation inhibitors (RhoGDIs) play important roles in various cellular processes, including cell migration, adhesion, and proliferation, by regulating the functions of the Rho GTPase family. Dissociation of Rho GTPases from RhoGDIs is necessary for their spatiotemporal activation and is dynamically regulated by several mechanisms, such as phosphorylation, sumoylation, and protein interaction. The expression of RhoGDIs has changed in many human cancers and become associated with the malignant phenotype, including migration, invasion, metastasis, and resistance to anticancer agents. Here, we review how RhoGDIs control the function of Rho GTPases by regulating their spatiotemporal activity and describe the regulatory mechanisms of the dissociation of Rho GTPases from RhoGDIs. We also discuss the role of RhoGDIs in cancer progression and their potential uses for therapeutic intervention.

scholarly journals Keratin 19 maintains E-cadherin localization at the cell surface and stabilizes cell-cell adhesion of MCF7 cells

2021 ◽  
Vol 15 (1) ◽  
pp. 1-17
Author(s):  
Sarah Alsharif ◽  
Pooja Sharma ◽  
Karina Bursch ◽  
Rachel Milliken ◽  
Van Lam ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Cell Surface ◽  
Mcf7 Cells ◽  
Keratin 19 ◽  
E Cadherin ◽  
Cell Cell
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