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Bladder pathologies, very common in the aged population, have a considerable negative impact on quality of life. Novel targets are needed to design drugs and combinations to treat diseases such as overactive bladder and bladder cancers. A promising new target is the ubiquitous Rho GTPase Rac1, frequently dysregulated and overexpressed in bladder pathologies. We have analyzed the roles of Rac1 in different bladder pathologies, including bacterial infections, diabetes-induced bladder dysfunctions and bladder cancers. The contribution of the Rac1 protein to tumorigenesis, tumor progression, epithelial-mesenchymal transition of bladder cancer cells and their metastasis has been analyzed. Small molecules selectively targeting Rac1 have been discovered or designed, and two of them—NSC23766 and EHT 1864—have revealed activities against bladder cancer. Their mode of interaction with Rac1, at the GTP binding site or the guanine nucleotide exchange factors (GEF) interaction site, is discussed. Our analysis underlines the possibility of targeting Rac1 with small molecules with the objective to combat bladder dysfunctions and to reduce lower urinary tract symptoms. Finally, the interest of a Rac1 inhibitor to treat advanced chemoresistance prostate cancer, while reducing the risk of associated bladder dysfunction, is discussed. There is hope for a better management of bladder pathologies via Rac1-targeted approaches. [ABSTRACT FROM AUTHOR]

The distributions of the rac1, rhoA and cdc42 proteins in respiratory syncytial virus (RSV) infected cells was examined. All three rhoGTPases were detected within inclusion bodies, and while the rhoA and rac1 proteins were associated with virus filaments, only the rac1 protein was localised throughout the virus filaments. RSV infection led to increased rac1 protein activation, and using the rac1 protein inhibitor NS23766 we provided evidence that the increased rac1 activation occurred at the site of RSV assembly and facilitated F-actin remodeling during virus morphogenesis. A non-infectious virus-like particle (VLP) assay showed that the RSV VLPs formed in lipid-raft microdomains containing the rac1 protein, together with F-actin and filamin-1 (cell proteins associated with virus filaments). This provided evidence that the virus envelope proteins are trafficked to membrane microdomains containing the rac1 protein. Collectively, these data provide evidence that the rac1 protein plays a direct role in the RSV assembly process. • The Rac1 protein is recruited to sites of respiratory syncytial virus assembly. • The Rac1 protein is activated in respiratory syncytial virus infected cells. • The Rac1 protein plays a role in respiratory syncytial virus morphogenesis. [ABSTRACT FROM AUTHOR]

In hypertensive retinopathy, the retinal damage due to high blood pressure is accompanied by increased expression of Glial Fibrillary Acidic Protein (GFAP), which indicates a role of neuroinflammatory processes in such a retinopathy. Proteins belonging to the Rho GTPase family, particularly Rac1, are involved in the activation of Müller glia and in the progression of photoreceptor degeneration, and may thus represent a novel candidate for therapeutic intervention following central nervous system inflammation. In this paper, we have observed that topical administration as eye drops of Cytotoxic Necrotizing Factor 1 (CNF1), a Rho GTPase modulator, surprisingly improves electrophysiological and behavioral visual performances in aged spontaneously hypertensive rats. Furthermore, such functional improvement is accompanied by a reduction of Rac1 activity and retinal GFAP expression. Our results suggest that Rac1 inhibition through CNF1 topical administration may represent a new strategy to target retinal gliosis. • Rac1 may represent a novel candidate for therapeutic intervention following retinopathy. • CNF1 improves electrophysiological and behavioral visual performances in aged spontaneously hypertensive rats. • CNF1 topical administration, through Rac1 inhibition, may constitute a new therapeutic approach to target retinal gliosis. [ABSTRACT FROM AUTHOR]

Excitation-inhibition balance is critical for maintaining proper functioning of the cerebral cortex, as evident from electrophysiological and modeling studies, and it is also important for animal behavior (Yizhar et al., 2011). In the cerebral cortex, excitation is provided by glutamate release from pyramidal neurons, while inhibition is provided by GABA release from several types of interneurons. Many neuropsychiatric disorders, such as epilepsy, anxiety, schizophrenia and autism exhibit an imbalance between the excitatory and inhibitory mechanisms of cortical circuits within key brain regions as prefrontal cortex or hippocampus, primarily through dysfunctions in the inhibitory system (Lewis, Volk, & Hashimoto, 2003; Marín, 2012) Given the significant role of GABAergic inhibition in shaping proper function of the cerebral cortex, we used a mouse model of developmentally decreased GABAergic inhibition in order to examine its effects in network properties, namely basal synaptic transmission, synaptic plasticity and dendritic morphology of pyramidal neurons. For our study, we used mice (postnatal day 20-30) in which the Rac1 protein was deleted from Nkx2.1-expressing neurons (Vidaki et al., 2012), (Rac1fl/flNkx2.1 +/cre) referred as Rac1 KO mice, and heterozygous (Rac1+/flNkx2.1 +/cre) or control (Rac1+/flNkx2.1 +/+) mice. The specific ablation of Rac1 protein from NKx2.1-expressing MGE-derived progenitors leads to a perturbation of their cell cycle exit resulting in decreased number of interneurons in the cortex(Vidaki et al, 2012). We prepared brain slices from the prefrontal cortex and recorded field excitatory postsynaptic potentials (fEPSPs) from layer II neurons while stimulating axons in layer II. We find that the evoked fEPSPs are decreased in Rac1 KO mice compared to Rac1 heterozygous or control mice. This could suggest that the decreased GABAergic inhibition causes network alterations that result in reduced glutamatergic function. Furthermore, we tested whether synaptic plasticity properties of intra-cortical layer II synapses are affected. In adult control mice, tetanic stimulation results in long-term potentiation that lasts at least 50 min (Konstantoudaki et al, 2013). In control mice of the age tested in this study (PD 20-30), LTP could not be induced with the same stimulation. However, we find that Rac1 KO mice do express long-term potentiation. We next studied the dendritic morphology of layer II neurons in the prefrontal cortex, in an effort to identify the mechanism by which Rac1 KO mice exhibit LTP, while the control mice of the same age do not. For this, we stained mouse brains of Rac1 KO and Rac1 heterozygous mice with the Golgi-Cox method. We analyzed the number of secondary apical dendrites, their thickness, as well as the number of spines. We find that the dendrites of pyramidal neurons of Rac1 KO mice have decreased thickness and increased number of spines compared to pyramidal neurons from Rac1 heterozygous mice. These findings could also provide a mechanistic explanation for the presence of LTP in Rac1 KO mice. In conclusion, we find that decreased inhibition during development alters the morphological and functional characteristics of pyramidal neurons in layer II prefrontal cortex of mice. These alterations could provide a cellular substrate for emotional and cognitive dysfunctions present in these mice (Konstantoudaki et al, 2012).

Background: Cancer metastasis is the most important cause of cancer death and different treatment strategies have targeted on preventing the occurrence of metastasis. Quercetin is a flavonoid and widely used as an antioxidant and recent studies have discovered its anticancer and antiproliferative capabilities. Rac1 is protein known to involve in tumor invasion and metastases. Objectives: In this study, we investigated the effect of quercetin on expression of Rac1 protein. Materials and Methods: In this experimental study, HeLa cells were treated with quercetin at 2 concentrations (20 and 40 µM) for 24 hours and then cell lysate was assessed by Western blotting analysis to investigate the impact of quercetin on expression of Rac1 protein. Results: Quercetin significantly decreased Rac1 expression of HeLa cells assessed by western blotting, in dose-dependent manners (P < 0.05). Conclusions: This study showed that quercetin decreased Rac1 expression as a marker of metastasis in cervical cancer cells. Therefore, the quercetin may provide an effective new strategy to reduce of tumor metastasis. Conclusions: This study showed that quercetin decreased Rac1 expression as a marker of metastasis in cervical cancer cells. Therefore, the quercetin may provide an effective new strategy to reduce of tumor metastasis. [ABSTRACT FROM AUTHOR]

Despite novel targeted and immunotherapies, the prognosis remains bleak for patients with hepatocellular carcinoma (HCC), especially for advanced and/or metastatic forms. The rapid emergence of drug resistance is a major obstacle in the success of chemo-, targeted-, immuno-therapies of HCC. Novel targets are needed. The prominent roles of the small GTPase Rac1 in the development and progression of HCC are discussed here, together with its multiple protein partners, and the targeting of Rac1 with RNA-based regulators and small molecules. We discuss the oncogenic functions of Rac1 in HCC, including the contribution of Rac1 mutants and isoform Rac1b. Rac1 is a ubiquitous target, but the protein is frequently overexpressed and hyperactivated in HCC. It contributes to the aggressivity of the disease, with key roles in cancer cell proliferation, tumor metastasis and resistance to treatment. Small molecule targeting Rac1, indirectly or directly, have shown anticancer effects in HCC experimental models. Rac1-binding agents such as EHT 1864 and analogues offer novel opportunities to combat HCC. We discuss the different modalities to repress Rac1 overactivation in HCC with small molecules and the combination with reference drugs to promote cancer cell death and to repress cell invasion. We highlight the necessity to combine Rac1-targeted approach with appropriate biomarkers to select Rac1 activated tumors. Our analysis underlines the prominent oncogenic functions of Rac1 in HCC and discuss the modalities to target this small GTPase. Rac1 shall be considered as a valid target to limit the acquired and intrinsic resistance of HCC tumors and their metastatic potential. [Display omitted] [ABSTRACT FROM AUTHOR]

Increase of microvascular permeability is one of the most important pathological events in the pathogenesis of trauma and burn injury. Massive leakage of fluid from vascular space leads to lose of blood plasma and decrease of effective circulatory blood volume, resulting in formation of severe tissue edema, hypotension or even shock, especially in severe burn injury. Fluid resuscitation has been the only valid approach to sustain patient’s blood volume for a long time, due to the lack of overall and profound understanding of the mechanisms of vascular hyperpermeability response. There is an emerging concept in recent years that some so-called barrier stabilizing mediators play a positive role in preventing the increase of vascular permeability. These mediators may be released in response to proinflammatory mediators and serve to restore endothelial barrier function. Some of these stabilizing mediators are important even in quiescent state because they preserve basal vascular permeability at low levels. This review introduces some of these mediators and reveals their underlying signaling mechanisms during endothelial barrier enhancing process. [ABSTRACT FROM AUTHOR]

To investigate the effect of autoimmune regulator (AIRE) on phagocytic clearance of apoptotic cells, a recombinant expression vector containing full-length human AIRE cDNA was transfected into 16HBE cells. After incubation with transfected 16HBE cells, engulfment of apoptotic HL-60 cells induced by camptothecin was detected by myeloperoxidase (MPO) staining. The change in the expression of Rac 1 in transfected 16HBE cells was determined by RT-PCR and Western blotting. The results showed that the phagocytosis percentage of the experimental group, the mock transfection group and the negative control group (non-apoptotic cells) was (25.50±3.67)%, (6.25±1.58)% and (1.0±0.67)%, respectively. Moreover, the expressions of Rac 1 mRNA and protein were up-regulated in AIRE-transfected 16HBE cells, suggesting that AIRE may function as a regulator in the phagocytic clearance of apoptotic cells by promoting the expression of Rac 1. [ABSTRACT FROM AUTHOR]

The activity of NADPH oxidase (NOX) is blocked by nitric oxide (NO). Hydrogen sulfide (H2S) is also produced by blood vessels. It is reasonable to suggest that H2S may have similar actions to NO on NOX. In order to test this hypothesis, the effect of sodium hydrosulfide (NaHS) on O2– formation, the expression of NOX-1 (a catalytic subunit of NOX) and Rac1 activity (essential for full NOX activity) in isolated vascular smooth muscle cells (hVSMCs) was investigated. hVSMCs were incubated with the thromboxane A2 analogue U46619 ± NaHS for 1 or 16 h, and O2– formation, NOX-1 expression and Rac1 activity were assessed. The possible interaction between H2S and NO was also studied by using an NO synthase inhibitor, L-NAME, and an NO donor, DETA-NONOate. The role of KATP channels was studied by using glibenclamide. NaHS inhibited O2– formation following incubation of 1 h (IC50, 30 nM) and 16 h (IC50, 20 nM), blocked NOX-1 expression and inhibited Rac1 activity. These inhibitory effects of NaHS were mediated by the cAMP-protein-kinase-A axis. Exogenous H2S prevents NOX-driven intravascular oxidative stress through an a priori inhibition of Rac1 and downregulation of NOX-1 protein expression, an effect mediated by activation of the adenylylcyclase-cAMP-protein-kinase-G system by H2S. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]