Search results for "Rac GTP-Binding Proteins"
showing 10 items of 12 documents
Tobacco cells contain a protein, immunologically related to the neutrophil small G protein Rac2 and involved in elicitor-induced oxidative burst.
1997
Abstract Suspension-cultured cells of Nicotiana tabacum generated active oxygen species (AOS) when they were treated with the proteinaceous elicitor, cryptogein. This response was blocked by diphenylene iodonium, an inhibitor of the neutrophil NADPH oxidase. When microsomal extracts of tobacco cells were probed with an antibody directed against the human small G protein Rac2, two immunoreactive proteins were detected at 18.5 and 20.5 kDa. The same experiment performed with cytosolic extracts of tobacco cells led to the observation of a strong immunoreactive protein at 21.5 kDa only in the cryptogein-treated cells. The appearance of this cytosolic protein was related to the production of AOS…
7-Keto-Cholesterol and Cholestan-3beta, 5alpha, 6beta-Triol Induce Eryptosis through Distinct Pathways Leading to NADPH Oxidase and Nitric Oxide Synt…
2019
Background/aims We showed that patho-physiological concentrations of either 7-keto-cholesterol (7-KC), or cholestane-3beta, 5alpha, 6beta-triol (TRIOL) caused the eryptotic death of human red blood cells (RBC), strictly dependent on the early production of reactive oxygen species (ROS). The goal of the current study was to assess the contribution of the erythrocyte ROS-generating enzymes, NADPH oxidase (RBC-NOX), nitric oxide synthase (RBC-NOS) and xanthine oxido-reductase (XOR) to the oxysterol-dependent eryptosis and pertinent activation pathways. Methods Phosphatidylserine exposure at the cell surface was estimated from annexin-V-binding, reactive oxygen/nitrogen species (RONS) and nitri…
Visualizing the spatiotemporal map of Rac activation in bovine aortic endothelial cells under laminar and disturbed flows.
2017
Disturbed flow can eliminate the alignment of endothelial cells in the direction of laminar flow, and significantly impacts on atherosclerosis in collateral arteries near the bifurcation and high curvature regions. While shear stress induced Rac polarity has been shown to play crucial roles in cell polarity and migration, little is known about the spatiotemporal map of Rac under disturbed flow, and the mechanism of flow-induced cell polarity still needs to be elucidated. In this paper, disturbed flow or laminar flow with 15 dyn/cm2 of average shear stress was applied on bovine aortic endothelial cells (BAECs) for 30 minutes. A genetically-encoded PAK-PBD-GFP reporter was transfected into BA…
Impact of NADPH oxidase functional polymorphisms in acute myeloid leukemia induction chemotherapy.
2016
Efficacy and toxicity of anthracycline treatment in acute myeloid leukemia (AML) is mediated by reactive oxygen species (ROS). NADPH oxidase is the major endogenous source of ROS and a key mediator of oxidative cardiac damage. The impact of NADPH oxidase polymorphisms (CYBA:rs4673, NCF4:rs1883112, RAC2:rs13058338) was evaluated in 225 adult de novo AML patients. Variant alleles of NCF4 and RAC2 were related to higher complete remission (P=0.035, P=0.016), and CYBA homozygous variant showed lower overall survival with recessive model (P=0.045). Anthracycline-induced cardiotoxicity was associated to NCF4 homozygous variant (P=0.012) and CYBA heterozygous genotype (P=0.027). Novel associations…
Azathioprine suppresses ezrin-radixin-moesin-dependent T cell-APC conjugation through inhibition of Vav guanosine exchange activity on rac proteins
2006
Abstract We have shown recently that the azathioprine metabolite 6-Thio-GTP causes immunosuppression by blockade of GTPase activation in T lymphocytes. In the present study, we describe a new molecular mechanism by which 6-Thio-GTP blocks GTPase activation. Although 6-Thio-GTP could bind to various small GTPases, it specifically blocked activation of Rac1 and Rac2 but not of closely related Rho family members such as Cdc42 and RhoA in primary T cells upon stimulation with αCD28 or fibronectin. Binding of 6-Thio-GTP to Rac1 did not suppress Rac effector coupling directly but blocked Vav1 exchange activity upon 6-Thio-GTP hydrolysis, suggesting that 6-Thio-GTP loading leads to accumulation of…
Ultraviolet light-induced apoptotic death is impaired by the HMG-CoA reductase inhibitor lovastatin.
2003
HMG-CoA reductase inhibitors (i.e., statins) attenuate C-terminal isoprenylation of Rho GTPases, thereby inhibiting UV-C-induced activation of c-Jun-N-terminal kinases/stress-activated protein kinases (JNKs/SAPKs). Inhibition of UV-C-triggered JNK/SAPK activation by lovastatin is due to inhibition of Rac-SEK1/MKK4-mediated phosphorylation of JNKs/SAPKs at Thr183/Tyr185. UV-C-stimulated phosphorylation of p38 kinase (Thr180/Tyr182) is also impaired by lovastatin. Cell killing provoked by UV-C irradiation was significantly inhibited by lovastatin. This was paralleled by a reduced frequency of chromosomal aberrations, accelerated recovery from UV-C-induced transient replication blockage, inhib…
Cloning of Rac and Rho-GDI from tobacco using an heterologous two-hybrid screen.
2000
International audience; To examine whether molecular similarities exist between the animal and plant Rho GTPase signaling pathways, we have developed a heterologous two-hybrid screening method. By this technique, we have cloned a cDNA encoding a tobacco Rac-like protein able to interact with a mammalian Rho-GDI. In a second screen this tobacco Rac was used as a bait and a tobacco homologue of Rho-GDI was identified. These results show that some components of the animal and plant Rac signaling pathways are similar enough to allow their interaction in an heterologous approach. Moreover these data suggest a similar regulation of Rho GTPases in animals and plants.
Rac1 GTPase, a multifunctional player in the regulation of genotoxic stress response
2013
The Ras-related C3 botulinum toxin substrate 1 (Rac1) belongs to the Ras-homologous (Rho) family of small GTPases, which transduce signals from the outside to the inside of a cell. Rac1 becomes activated upon ligand binding of a variety of receptors, including receptor tyrosine kinases and heterotrimeric G-protein-coupled receptors. After GTP loading by guanine exchange factors (GEFs), GTP-bound Rac1 engages numerous effector proteins, thereby eventually regulating cell motility and adhesion, cell cycle progression through G1, mitosis and meiosis, as well as cell death and metastasis.1 Besides, Rac1 adjusts cellular responses to genotoxic agents, such as UV light and alkylating agents, by r…
Ras, Rap, and Rac Small GTP-binding Proteins Are Targets for Clostridium sordellii Lethal Toxin Glucosylation
1996
Lethal toxin (LT) from Clostridium sordellii is one of the high molecular mass clostridial cytotoxins. On cultured cells, it causes a rounding of cell bodies and a disruption of actin stress fibers. We demonstrate that LT is a glucosyltransferase that uses UDP-Glc as a cofactor to covalently modify 21-kDa proteins both in vitro and in vivo. LT glucosylates Ras, Rap, and Rac. In Ras, threonine at position 35 was identified as the target amino acid glucosylated by LT. Other related members of the Ras GTPase superfamily, including RhoA, Cdc42, and Rab6, were not modified by LT. Incubation of serum-starved Swiss 3T3 cells with LT prevents the epidermal growth factor-induced phosphorylation of m…
NG2 regulates directional migration of oligodendrocyte precursor cells via Rho GTPases and polarity complex proteins.
2013
The transmembrane proteoglycan NG2 is expressed by oligodendrocyte precursor cells (OPC), which migrate to axons during developmental myelination and remyelinate in the adult after migration to injured sites. Highly invasive glial tumors also express NG2. Despite the fact that NG2 has been implicated in control of OPC migration, its mode of action remains unknown. Here, we show in vitro and in vivo that NG2 controls migration of OPC through the regulation of cell polarity. In stab wounds in adult mice we show that NG2 controls orientation of OPC toward the wound. NG2 stimulates RhoA activity at the cell periphery via the MUPP1/Syx1 signaling pathway, which favors the bipolar shape of migrat…