scholarly journals Coupling of Rho family GTPases during mesenchymal-to-epithelial-like transitions

2018 ◽  
Author(s):  
Christopher P. Toret ◽  
Pruthvi C. Shivakumar ◽  
Pierre-françois Lenne ◽  
Andre Le Bivic
Keyword(s):  
Rho Gtpases ◽  
Rho Gtpase ◽  
Leading Edge ◽  
Dorsal Closure ◽  
Developmental Processes ◽  
Rho Family Gtpases ◽  
Rho Protein ◽  
Cellular Context ◽  
Rho Family

ABSTRACTMany metazoan developmental processes require cells to transition between migratory mesenchymal- and adherent epithelial-like states. These transitions require Rho GTPase-mediated actin rearrangements downstream of integrin and cadherin pathways. A regulatory toolbox of GEF and GAP proteins precisely coordinates Rho protein activities, yet defining the involvement of specific regulators within a cellular context remains a challenge due to overlapping and coupled activities. Here we demonstrate that Drosophila dorsal closure is a simple, powerful model for Rho GTPase regulation during leading edge to cadherin contact transitions. During these transitions a Rac GEF elmo-dock complex regulates both lamellipodia and Rho1-dependent, actomyosin-mediated tension at initial cadherin contacts. Moreover, the Drosophila Rho GAP arhgap21 ortholog controls Rac and Rho GTPases during the same processes and genetically regulates the elmo-dock complex. This study presents a fresh framework to understand the inter-relationship between GEF and GAP proteins that tether Rac and Rho cycles during developmental processes.

scholarly journals Electrostatic Forces Mediate the Specificity of RHO GTPase-GDI Interactions

2021 ◽  
Vol 22 (22) ◽  
pp. 12493
Author(s):  
Niloufar Mosaddeghzadeh ◽  
Neda S. Kazemein Jasemi ◽  
Jisca Majolée ◽  
Si-Cai Zhang ◽  
Peter L. Hordijk ◽  
...  
Keyword(s):  
Rho Gtpases ◽  
Rho Gtpase ◽  
Kinetic Mechanism ◽  
Membrane Extraction ◽  
Rho Protein ◽  
Switch Regions ◽  
Charged Clusters ◽  
Rho Family ◽  
Hydrophobic Cleft

Three decades of research have documented the spatiotemporal dynamics of RHO family GTPase membrane extraction regulated by guanine nucleotide dissociation inhibitors (GDIs), but the interplay of the kinetic mechanism and structural specificity of these interactions is as yet unresolved. To address this, we reconstituted the GDI-controlled spatial segregation of geranylgeranylated RHO protein RAC1 in vitro. Various biochemical and biophysical measurements provided unprecedented mechanistic details for GDI function with respect to RHO protein dynamics. We determined that membrane extraction of RHO GTPases by GDI occurs via a 3-step mechanism: (1) GDI non-specifically associates with the switch regions of the RHO GTPases; (2) an electrostatic switch determines the interaction specificity between the C-terminal polybasic region of RHO GTPases and two distinct negatively-charged clusters of GDI1; (3) a non-specific displacement of geranylgeranyl moiety from the membrane sequesters it into a hydrophobic cleft, effectively shielding it from the aqueous milieu. This study substantially extends the model for the mechanism of GDI-regulated RHO GTPase extraction from the membrane, and could have implications for clinical studies and drug development.

scholarly journals A Novel Testis-specific GTPase Serves as a Link to Proteasome Biogenesis: Functional Characterization of RhoS/RSA-14-44 in Spermatogenesis

2010 ◽  
Vol 21 (24) ◽  
pp. 4312-4324 ◽  
Author(s):  
Ning Zhang ◽  
Junbo Liang ◽  
Yongqiang Tian ◽  
Ligang Yuan ◽  
Lan Wu ◽  
...  
Keyword(s):  
Rho Gtpases ◽  
Rho Gtpase ◽  
Wide Spectrum ◽  
Functional Characterization ◽  
Male Reproduction ◽  
Spermatogenic Cells ◽  
Functional Connection ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
The Stability

Most Rho family GTPases serve as key molecular switches in a wide spectrum of biological processes. An increasing number of studies have expanded their roles to the spermatogenesis. Several members of Rho family have been confirmed to be essential for mammalian spermatogenesis, but the precise roles of this family in male reproduction have not been well studied yet. Here we report a surprising function of an atypical and testis-specific Rho GTPase, RSA-14-44 in spermatogenesis. Featured by unique structural and expressional patterns, RSA-14-44 is distinguished from three canonical members of Rho cluster. Thus, we define RSA-14-44 as a new member of Rho GTPases family and rename it RhoS (Rho in spermatogenic cells). RhoS associates with PSMB5, a catalytic subunit of the proteasome, in a series of stage-specific spermatogenic cells. More importantly, RhoS does not directly modulate the cellular proteasome activity, but participates in regulating the stability of “unincorporated” PSMB5 precursors. Meanwhile, our data demonstrate that the activation of RhoS is prerequisite for negatively regulating the stability of PSMB5 precursors. Therefore, our finding uncovers a direct and functional connection between the Rho GTPase family and the pathway of proteasome biogenesis and provide new clues for deciphering the secrets of spermatogenesis.

Rho family GTPases

2012 ◽  
Vol 40 (6) ◽  
pp. 1378-1382 ◽  
Author(s):  
Alan Hall
Keyword(s):  
Actin Cytoskeleton ◽  
Rho Gtpases ◽  
Cellular Response ◽  
Molecular Switches ◽  
Effector Proteins ◽  
Eukaryotic Cells ◽  
Cell Behaviour ◽  
Wide Range ◽  
Rho Family Gtpases ◽  
Rho Family

Rho GTPases comprise a family of molecular switches that control signal transduction pathways in eukaryotic cells. A conformational change induced upon binding GTP promotes an interaction with target (effector) proteins to generate a cellular response. A highly conserved function of Rho GTPases from yeast to humans is to control the actin cytoskeleton, although, in addition, they promote a wide range of other cellular activities. Changes in the actin cytoskeleton drive many dynamic aspects of cell behaviour, including morphogenesis, migration, phagocytosis and cytokinesis, and the dysregulation of Rho GTPases is associated with numerous human diseases and disorders.

scholarly journals Grit, a GTPase-Activating Protein for the Rho Family, Regulates Neurite Extension through Association with the TrkA Receptor and N-Shc and CrkL/Crk Adapter Molecules

2002 ◽  
Vol 22 (24) ◽  
pp. 8721-8734 ◽  
Author(s):  
Takeshi Nakamura ◽  
Misako Komiya ◽  
Kiyoaki Sone ◽  
Eiji Hirose ◽  
Noriko Gotoh ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Neuronal Cells ◽  
Small Gtpases ◽  
Actin Dynamics ◽  
Gtpase Activating Protein ◽  
Interacting Protein ◽  
High Affinity Receptor ◽  
Rho Family

ABSTRACT Neurotrophins are key regulators of the fate and shape of neuronal cells and act as guidance cues for growth cones by remodeling the actin cytoskeleton. Actin dynamics is controlled by Rho GTPases. We identified a novel Rho GTPase-activating protein (Grit) for Rho/Rac/Cdc42 small GTPases. Grit was abundant in neuronal cells and directly interacted with TrkA, a high-affinity receptor for nerve growth factor (NGF). Another pool of Grit was recruited to the activated receptor tyrosine kinase through its binding to N-Shc and CrkL/Crk, adapter molecules downstream of activated receptor tyrosine kinases. Overexpression of the TrkA-binding region of Grit inhibited NGF-induced neurite elongation. Further, we found some tendency for neurite promotion in full-length Grit-overexpressing PC12 cells upon NGF stimulation. These results suggest that Grit, a novel TrkA-interacting protein, regulates neurite outgrowth by modulating the Rho family of small GTPases.

scholarly journals Differential activation and function of Rho GTPases during Salmonella–host cell interactions

2006 ◽  
Vol 175 (3) ◽  
pp. 453-463 ◽  
Author(s):  
Jayesh C. Patel ◽  
Jorge E. Galán
Keyword(s):  
Rho Gtpases ◽  
Food Poisoning ◽  
Bacterial Pathogen ◽  
Cellular Responses ◽  
Host Cells ◽  
Nucleotide Exchange ◽  
Exchange Factor ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
And Function

Salmonella enterica, the cause of food poisoning and typhoid fever, has evolved sophisticated mechanisms to modulate Rho family guanosine triphosphatases (GTPases) to mediate specific cellular responses such as actin remodeling, macropinocytosis, and nuclear responses. These responses are largely the result of the activity of a set of bacterial proteins (SopE, SopE2, and SopB) that, upon delivery into host cells via a type III secretion system, activate specific Rho family GTPases either directly (SopE and SopE2) or indirectly (SopB) through the stimulation of an endogenous exchange factor. We show that different Rho family GTPases play a distinct role in Salmonella-induced cellular responses. In addition, we report that SopB stimulates cellular responses by activating SH3-containing guanine nucleotide exchange factor (SGEF), an exchange factor for RhoG, which we found plays a central role in the actin cytoskeleton remodeling stimulated by Salmonella. These results reveal a remarkable level of complexity in the manipulation of Rho family GTPases by a bacterial pathogen.

scholarly journals Rho family GTPases control entry of Shigella flexneri into epithelial cells but not intracellular motility

1999 ◽  
Vol 112 (13) ◽  
pp. 2069-2080 ◽  
Author(s):  
J. Mounier ◽  
V. Laurent ◽  
A. Hall ◽  
P. Fort ◽  
M.F. Carlier ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Rho Gtpases ◽  
Actin Polymerization ◽  
Rho Gtpase ◽  
Shigella Flexneri ◽  
Intercellular Junctions ◽  
Small Gtpases ◽  
Comet Tail ◽  
Rho Family ◽  
Intracellular Motility

Shigella flexneri, an invasive bacterial pathogen, promotes formation of two cytoskeletal structures: the entry focus that mediates bacterial uptake into epithelial cells and the actin-comet tail that enables the bacteria to spread intracellularly. During the entry step, secretion of bacterial invasins causes a massive burst of subcortical actin polymerization leading the formation of localised membrane projections. Fusion of these membrane ruffles leads to bacterial internalization. Inside the cytoplasm, polar expression of the IcsA protein on the bacterial surface allows polymerization of actin filaments and their organization into an actin-comet tail leading to bacterial spread. The Rho family of small GTPases plays an essential role in the organization and regulation of cellular cytoskeletal structures (i.e. filopodia, lamellipodia, adherence plaques and intercellular junctions). We show here that induction of Shigella entry foci is controlled by the Cdc42, Rac and Rho GTPases, but not by RhoG. In contrast, actin-driven intracellular motility of Shigella does not require Rho GTPases. Therefore, Shigella appears to manipulate the epithelial cell cytoskeleton both by Rho GTPase-dependent and -independent processes.

scholarly journals Mechanochemical coupling and junctional forces during collective cell migration

2019 ◽  
Author(s):  
J. Bui ◽  
D. E. Conway ◽  
R. L. Heise ◽  
S.H. Weinberg
Keyword(s):  
Cell Migration ◽  
Rho Gtpases ◽  
Cancer Metastasis ◽  
Rho Gtpase ◽  
Critical Role ◽  
Leading Edge ◽  
Collective Cell Migration ◽  
Gtpase Activity ◽  
Modeling Framework ◽  
Cell Cell

ABSTRACTCell migration, a fundamental physiological process in which cells sense and move through their surrounding physical environment, plays a critical role in development and tissue formation, as well as pathological processes, such as cancer metastasis and wound healing. During cell migration, dynamics are governed by the bidirectional interplay between cell-generated mechanical forces and the activity of Rho GTPases, a family of small GTP-binding proteins that regulate actin cytoskeleton assembly and cellular contractility. These interactions are inherently more complex during the collective migration of mechanically coupled cells, due to the additional regulation of cell-cell junctional forces. In this study, we present a minimal modeling framework to simulate the interactions between mechanochemical signaling in individual cells and interactions with cell-cell junctional forces during collective cell migration. We find that migration of individual cells depends on the feedback between mechanical tension and Rho GTPase activity in a biphasic manner. During collective cell migration, waves of Rho GTPase activity mediate mechanical contraction/extension and thus synchronization throughout the tissue. Further, cell-cell junctional forces exhibit distinct spatial patterns during collective cell migration, with larger forces near the leading edge. Larger junctional force magnitudes are associated with faster collective cell migration and larger tissue size. Simulations of heterogeneous tissue migration exhibit a complex dependence on the properties of both leading and trailing cells. Computational predictions demonstrate that collective cell migration depends on both the emergent dynamics and interactions between cellular-level Rho GTPase activity and contractility, and multicellular-level junctional forces.

scholarly journals The novel RacE-binding protein GflB sharpens Ras activity at the leading edge of migrating cells

2016 ◽  
Vol 27 (10) ◽  
pp. 1596-1605 ◽  
Author(s):  
Hiroshi Senoo ◽  
Huaqing Cai ◽  
Yu Wang ◽  
Hiromi Sesaki ◽  
Miho Iijima
Keyword(s):  
Rho Gtpases ◽  
Rho Gtpase ◽  
Gene Knockout ◽  
Binding Protein ◽  
Affinity Purification ◽  
Leading Edge ◽  
The Novel ◽  
Gradient Sensing ◽  
Signaling Events ◽  
Migrating Cells

Directional sensing, a process in which cells convert an external chemical gradient into internal signaling events, is essential in chemotaxis. We previously showed that a Rho GTPase, RacE, regulates gradient sensing in Dictyostelium cells. Here, using affinity purification and mass spectrometry, we identify a novel RacE-binding protein, GflB, which contains a Ras GEF domain and a Rho GAP domain. Using biochemical and gene knockout approaches, we show that GflB balances the activation of Ras and Rho GTPases, which enables cells to precisely orient signaling events toward higher concentrations of chemoattractants. Furthermore, we find that GflB is located at the leading edge of migrating cells, and this localization is regulated by the actin cytoskeleton and phosphatidylserine. Our findings provide a new molecular mechanism that connects directional sensing and morphological polarization.

scholarly journals Rho-family GTPases modulate Ca2+-dependent ATP release from astrocytes

2008 ◽  
Vol 295 (1) ◽  
pp. C231-C241 ◽  
Author(s):  
Andrew E. Blum ◽  
Sheldon M. Joseph ◽  
Ronald J. Przybylski ◽  
George R. Dubyak
Keyword(s):  
Rho Gtpases ◽  
Atp Release ◽  
Rho Kinase ◽  
Astrocytoma Cells ◽  
Gap Junction Channel ◽  
Rho Family Gtpases ◽  
Clostridium Difficile Toxin ◽  
Protease Activated Receptor 1 ◽  
Rho Family ◽  
Clostridium Difficile Toxin B

Previously, we reported that activation of G protein-coupled receptors (GPCR) in 1321N1 human astrocytoma cells elicits a rapid release of ATP that is partially dependent on a Gq/phophospholipase C (PLC)/Ca2+ mobilization signaling cascade. In this study we assessed the role of Rho-family GTPase signaling as an additional pathway for the regulation of ATP release in response to activation of protease-activated receptor-1 (PAR1), lysophosphatidic acid receptor (LPAR), and M3-muscarinic (M3R) GPCRs. Thrombin (or other PAR1 peptide agonists), LPA, and carbachol triggered quantitatively similar Ca2+ mobilization responses, but only thrombin and LPA caused rapid accumulation of active GTP-bound Rho. The ability to elicit Rho activation correlated with the markedly higher efficacy of thrombin and LPA, relative to carbachol, as ATP secretagogues. Clostridium difficile toxin B and Clostridium botulinum C3 exoenzyme, which inhibit Rho-GTPases, attenuated the thrombin- and LPA-stimulated ATP release but did not decrease carbachol-stimulated release. Thus the ability of certain Gq-coupled receptors to additionally stimulate Rho-GTPases acts to strongly potentiate a Ca2+-activated ATP release pathway. However, pharmacological inhibition of Rho kinase I/II or myosin light chain kinase did not attenuate ATP release. PAR1-induced ATP release was also reduced twofold by brefeldin treatment suggesting the possible mobilization of Golgi-derived, ATP-containing secretory vesicles. ATP release was also markedly repressed by the gap junction channel inhibitor carbenoxolone in the absence of any obvious thrombin-induced change in membrane permeability indicative of hemichannel gating.

scholarly journals Rac1 links leading edge and uropod events through Rho and myosin activation during chemotaxis

Blood ◽  
2006 ◽  
Vol 108 (8) ◽  
pp. 2814-2820 ◽  
Author(s):  
Kersi N. Pestonjamasp ◽  
Carol Forster ◽  
Chunxiang Sun ◽  
Elisabeth M. Gardiner ◽  
Ben Bohl ◽  
...  
Keyword(s):  
Rho Gtpases ◽  
Actin Polymerization ◽  
Critical Role ◽  
Leading Edge ◽  
Feedback System ◽  
Small Gtpases ◽  
Human Neutrophils ◽  
Trailing Edge ◽  
Rac Gtpases ◽  
Rho Family

Abstract Chemotactic responsiveness is crucial to neutrophil recruitment to sites of infection. During chemotaxis, highly divergent cytoskeletal programs are executed at the leading and trailing edge of motile neutrophils. The Rho family of small GTPases plays a critical role in cell migration, and recent work has focused on elucidating the specific roles played by Rac1, Rac2, Cdc42, and Rho during cellular chemotaxis. Rac GTPases regulate actin polymerization and extension of the leading edge, whereas Rho GTPases control myosin-based contraction of the trailing edge. Rac and Rho signaling are thought to crosstalk with one another, and previous research has focused on mutual inhibition of Rac and Rho signaling during chemotaxis. Indeed, polarization of neutrophils has been proposed to involve the activity of a negative feedback system where Rac activation at the front of the cell inhibits local Rho activation, and vice versa. Using primary human neutrophils and neutrophils derived from a Rac1/Rac2-null transgenic mouse model, we demonstrate here that Rac1 (and not Rac2) is essential for Rho and myosin activation at the trailing edge to regulate uropod function. We conclude that Rac plays both positive and negative roles in the organization of the Rhomyosin “backness” program, thereby promoting stable polarity in chemotaxing neutrophils.

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