In China, traditional Chinese medicine has been used for the treatment of influenza virus infection for many years [13, 14]. Artemisia scoparia Waldst and Kit is widely distributed in Xinjiang, China and com- monly used as a Uighur medicine, which has been used for preventing and treating cough, cold, and fever . Flavonoids extracted from A. scoparia have inhibitory activities against influenza viruses . Despite this fact, the antiviral study of cirsimaritin (CST), one of such flavonoids, has not been reported so far. In the present study, we demonstrated that CST (PubChem CID: 188323, Fig. 1a) inhibited the IAV. Interestingly, we found that IAV replication is inhibited after the downregulation of the NF-κB signal transductionpathway by CST.
The phosphatidylinositol 3-kinase(PI3K)-protein kinase B (Akt) signal transductionpathway is a crucial regulator of a number of cellular processes, including proliferation, differen- tiation, and cell survival. Activation of this pathway has been documented as a frequent occurrence in many types of human cancer (22, 51). A recent comprehensive microarray study with a large number of human hepatocellular carcinomas revealed that the activation of Akt1 is one of the most consistent fea- tures of HBV-induced HCC (7). Moreover, the PI3K-Akt pathway is activated during infection by many viruses, includ- ing HCV (45, 46). It is generally believed that the activation of the PI3K-Akt pathway by viruses inhibits apoptosis and pro- motes the survival of infected cells to favor viral replication (11). It is, therefore, interesting to know if the PI3K-Akt path- way regulates HBV replication. Our results demonstrate that the activation of this pathway inhibits HBV RNA transcription and consequently reduces viral DNA replication. Those obser- vations suggest a molecular basis for the observed inhibition of HBV replication during HCC oncogenesis and HCV coin- fection.
Sensory control of sporulation in Physarum polycephalum plasmodia is mediated by a branched signal- transductionpathway that integrates blue light, far-red light, heat shock and the starvation state. Mutants defective in the pathway were isolated and three phenotypes obtained: blue-blind, general-blind and light-independent sporulating. When plasmodia of the blue-blind mutant Blu1 were exposed to a pulse of blue light and subsequently fused to non-induced wild-type plasmodia, the resulting heterokaryons sporulated, indicating a functional blue- light photoreceptor in the mutant. When the general-blind mutant Nos1 was fused to a wild-type plasmodium which had been induced by light, sporulation of the heterokaryon was blocked. However, the dominant inhibition of sporulation by Nos1 was gradually lost with increasing time between induction by light and time of fusion, suggesting that Nos1 can be bypassed by the time- dependent formation of a downstream signal-transduction
In the present study, adenylate cyclase activation reduced the response to cadaverine to less than 50% of its unadapted response, while the responses to histamine, putrescine, agmatine, spermidine and spermine were not significantly affected. These results suggest that cadaverine, a 4-C diamine, may be linked to a different transductionpathway from the other polyamines, perhaps interacting with a receptor for the basic amino acid lysine. Phospholipase C inhibition had little effect on evoked responses to spermine and AGB. The failure of both forskolin and U-73122 to significantly affect evoked responses to AGB and spermine indicates that these odorants are unlikely to use either adenylate cyclase-mediated or phospholipase C-mediated transduction cascades. The signaling cascade activated by polyamines warrants further investigation.
Glucose also regulates the levels of Mth1 and Std1 in cells by regulating MTH1 and STD1 transcription via feedback and feedforward regulatory mechanisms that operate through two different glucose signal transduction pathways (15). Glucose- induced disappearance of Std1 is attenuated by feedback reg- ulation of STD1 expression via the Snf3/Rgt2-Rgt1 signal transductionpathway (Fig. 2), which causes STD1 expression to be induced by glucose, thereby replenishing Std1 soon after its degradation is initiated by addition of glucose to cells. We believe this feedback regulation evolved to provide sufficient levels of Std1 to ensure efficient reestablishment of repression of HXT expression as soon as cells exhaust the available glu- cose. Indeed, interruption of this regulation of STD1 expres- sion results in slower establishment of repression of HXT1 expression upon removal of glucose from cells (Fig. 3B). In contrast, Mth1 degradation is reinforced by glucose repression of MTH1 expression mediated by the Snf1-Mig1 glucose-sig- naling pathway. Disappearance of Mth1 is slowed in cells miss- ing Mig1 and Mig2 or lacking their binding site in the MTH1 promoter (Fig. 2). We believe the purpose of this regulation is to ensure rapid removal of Mth1 from cells when glucose becomes available so as to enable prompt induction of HXT gene expression. This idea is supported by our observation that interruption of this regulation results in delayed induction of HXT3 expression in response to glucose (Fig. 3A).
At each time points after exposure to STE, cells were washed twice with PBS and lysed by adding 1 ml of TRI- zol (Invitrogen, CA) followed by isolation of RNA following manufacturer’s instructions (RNeasy Qiagen). The mRNA was reverse-transcribed by using cDNA synthesis kit (iScript one-step, BioRad, CA) into cDNA and analyzed by real-time PCR (BioRad, iCycler, CA). RNA quality was assessed on Agilent Bioanalyzer (Agilent Technologies, CA). Real-Time PCR was performed using SYBR Green PCR reagents (BioRad, CA) with 100 ng of RNA and a pair of primers specific for the gene of interest. Each sample was tested in triplicate. Threshold values for target genes were normalized to beta-actin, and quantitative data was calculated using the ∆∆CT me- thods . The expression of 84 relevant and pathway-focused genes were evaluated in a 96-well plate using the RT 2 Profiler PCR array Human Signal TransductionPathway Finder (PAHS-014, SA Bioscience, Frederick, MD) and Human apoptosis pathway (PAHS- 012). Changes in cycle threshold (∆Ct) values for each gene were obtained by subtracting the mean threshold cycle (Ct) of the housekeeping genes (B2M, HPRT1, RPL13A, GAPDH, ACTB) from the threshold cycle value of the gene. Normalized transcription was calculated as 2 ^ ( −∆CT). The fold up- or down-regulation was calculated relative to the control by comparison of the normalized transcription of each gene. The genes that showed more than a 2-fold difference in expression were identified. Statistical analysis tools (including paired student t-test) provided by the manufacturer (SA BioSciences) with the qRT-PCR array kit was utilized to determine the level of significance in differential expression patterns. Significance was considered for genes that had p- value ≥ 0.05. Three independent experiments followed by three array runs were carried out for each time point.
Our results demonstrated that WNV inhibits one of the first steps of the IFN signal transductionpathway and, hence, pro- vided an explanation for previous observations made with WNV-infected mice and tissue culture cells (5, 27). Interac- tions between viral proteins and components of the innate immune response are major determinants in viral pathogene- sis. This fact is best exemplified with genetically modified mice that are deficient in their response to IFN- ␣ due to the lack of functional IFN- ␣ / ␤ receptors or STAT proteins and, as a con- sequence, rapidly succumb to viral infections (9, 26, 28). On the other hand, most, if not all, viruses depend on mechanisms to attenuate the IFN response for their survival (22). For example, certain parainfluenza viruses can inhibit the IFN pathway in human cells with the help of the accessory protein V that induces the proteasome-dependent degradation of STAT proteins (8, 30).
We suggest, therefore, that the binding of RANTES oli- gomers to cell-surface GAGs activates a signal transductionpathway(s) which involves herbimycin A-sensitive tyrosine ki- nases. Several signaling pathways activated by RANTES in T cells have been described (6, 7, 25, 43, 82, 87, 91, 93). At present, those involved in viral infectivity enhancement remain to be identified, as does the stage(s) in the life cycles of HIV-1 and other viruses that is affected by this signal(s). Syndecans are one group of prototypic proteoglycans that have been ex- tensively studied; their expression changes dramatically during cell development and differentiation and is influenced by cell activation (13). Syndecans and another proteoglycan, CD44, have been shown to associate with protein tyrosine kinases from the Src family (38, 69). Useful information might accrue from studies in these general areas.
the glycemic control of several diabetic patients under oral medications was significantly improved with a SXF regimen (Table 1). While more controlled clinical trials on SXF need to be conducted to further verify its hypoglycemic effect, few studies have yet been performed to unveil the mode of hypoglycemic action of SXF. To gain an insight into the hypoglycemic mechanism of SXF, we investigated its effects on the insulin signal transductionpathway, ie, a cascade of biochemical events required for the glycemic control in response to insulin. 13,15
Wnt signal transductionpathway and apoptosis I will briefly describe the mechanisms of classical wnt sig- naling. The wnt/wingless pathway was first discovered in Drosophila and mouse, and is one of the most interesting signal transductions, in which key components have mul- tiple functions. In vertebrate cells, it is named after wnt proteins, a family of highly conserved secreted signaling molecules . Insights into the mechanisms of wnt action have emerged from several systems: genetics in Droso- phila and C. elegans; biochemistry in cell culture; and ectopic gene expression in Xenopus embryos. Many wnt genes in the mouse have been mutated, leading to highly specific developmental defects. As currently understood, wnt proteins bind to receptors of the Frizzled family on the cell surface. Through several cytoplasmic relay com- ponents, the signal is transduced to β-catenin, which enters the nucleus to activate transcription of wnt target
We have used adenoviral-mediated gene transfer of a consti- tutively active (V12rac1) and dominant negative (N17rac1) isoform of rac1 to assess the role of this small GTPase in cardiac myocyte hypertrophy. Expression of V12rac1 in neonatal cardiac myocytes results in sarcomeric reorganiza- tion and an increase in cell size that is indistinguishable from ligand-stimulated hypertrophy. In addition, V12rac1 expression leads to an increase in atrial natriuretic peptide secretion. In contrast, expression of N17rac1, but not a trun- cated form of Raf-1, attenuated the morphological hyper- trophy associated with phenylephrine stimulation. Consis- tent with the observed effects on morphology, expression of V12rac1 resulted in an increase in new protein synthesis, while N17rac1 expression inhibited phenylephrine-induced leucine incorporation. These results suggest rac1 is an es- sential element of the signaling pathway leading to cardiac myocyte hypertrophy. ( J. Clin. Invest. 1998. 102:929–937.) Key words: GTPase • rac1 • myocyte • hypertrophy • signal transduction
We employed the NFκB signaling pathway inducer, TNF-α, to verify the effect of DAI treat- ment. As shown in Figure 6, after 1 hour of TNF-α treatment, RelA (p65) expression in- creased significantly. However, when cells were treated with E2 or DAI, the expression level of RelA (p65) decreased significantly compared to the control group, indicating that DAI is capable of inhibiting the NFκB signaling pathway even when the pathway is activated.
Abstract: A full-scale mathematical model of cellular networks normally involves a large number of variables and parameters. How to effectively develop manageable and reliable models is crucial for effective computation, analysis and design of such systems. The aim of model simplification is to eliminate parts of a model that are unimportant for the properties of interest. In this work, a model reduction strategy via hybrid inference is proposed for signal pathway networks. It integrates multiple techniques including conservation analysis, local sensitivity analysis, principal component analysis and flux analysis to identify the reactions and variables that can be considered to be eliminated from the full-scale model. Using an IκB-NF-κB signalling pathway model as an example, simulation analysis demonstrates that the simplified model quantitatively predicts the dynamic behaviours of the network.
In the further study, we focused on investigating the acti- vation states of IFNα-induced signal transduction path- ways in myeloma cellls. We observed that both STAT3 and STAT1 could be activated in the both two myeloma cell lines irrespective of growth outcome upon IFNα stimula- tion; while the activation state of ERK correlated tightly with the growth effect of IFN α (Fig. 2, 3 and 4). That means, the Ras/MAPK in stead of the JAK/STAT signal transductionpathway mainly contributed to the different response of myeloma cells to IFNα. Identification of the target gene(s) regulated by protein kinase ERK in the Ras/ MAPK pathway in IFN α -arrested and stimulated myeloma cells will be helpful to further elucidate the mechanism of IFN α on myeloma cells.
Blocking ICOS co-stimulation pathways to inhibit the activity of ITP T cells in immune tolerance induction provides a theoretical basis for the mechanism and treat- ment of ITP. Co-stimulatory signal blockage triggers T cells to produce specific immune tolerance to antigens. Previous studies have confirmed that the ITP CD28/B7 pathway is involved in T cell activation [40-42]. The B7 co-stimulation blockers CTLA4-Ig and CsA can block the co-stimulatory signal pathway and induce T cell tolerance. Blocking CD28 co-stimulation alone cannot induce T cell immune tolerance, suggesting the presence of other pathways that mediate T cell tolerance induction [2,43]. Additional research into the ICOS/ICOS-L co-stimulatory signal pathway is necessary to identify new mechanisms involved in ITP pathogenesis. Blocking the ICOS/ICOS-L co-stimulatory signal transductionpathway could be a new way to induce T cell tolerance in ITP.
inherited disorders of the RAS/MAPK signal transductionpathway that display hypertrophic cardiomyopathy (HCM); the model from the former paper was from a gain-of-function Raf1 mutation, and the model from the latter paper was from a protein tyrosine phosphatase, non- receptor type 11 (Ptpn11) mutated allele encoding Shp2 with impaired catalytic function. The two groups show that HCM arises from increased signaling through Erk1/2 and the mTor complex 1, respectively, and that those cardiac issues can be prevented or reversed with small-molecule therapies inhibiting the appropriate pathway. Aside from being the first studies of treatment for Noonan syndrome and related disorders in a mammalian system, these papers provide important insights into the role of RAS signaling in cardiac
How can bias in a drug screen be detected? Experimentally, bias can be difficult to assess because of the relatively small number of available ligands for each receptor. Results gleaned from one system may or may not indicate a systematic bias. Similarly, finding drugs that have been overlooked by a screen requires screening a library of compounds multiple times using multiple assays—an effort far too costly for most research groups to undertake. In light of these problems, we chose to look for bias using kinetic models of drug-target interactions. Kinetic models are used in pharmacology to describe the dynamics of known physical interactions between different parts of the signal transductionpathway. By taking a modeling instead of an experimental approach, we are not limited by the number of available compounds and can therefore scan the whole range of possible drug properties with a variety of assay formats.
coefficients, based on which, different methods were used to discard parameters that have less influence on the model dynamics. 7 Using the Monte Carlo method, Cho et al. employed multi-parametric global sensitivity analysis on the TNFa-mediated NF-kB signal transductionpathway for experimental design. 8 Schwacke and Voit presented a Taylor integration method for the efficient computation of time- dependent sensitivities for generalized mass action systems, then investigated the effects of different initial species concentrations on the system dynamics. 9
Gliosis is often a preclinical pathological finding in neurodegenerative diseases, including prion diseases, but the mechanisms facilitating gliosis and neuronal damage in these diseases are not understood. To expand our knowledge of the neuroinflamma- tory response in prion diseases, we assessed the expression of key genes and proteins involved in the inflammatory response and signal transduction in mouse brain at various times after scrapie infection. In brains of scrapie-infected mice at pre- and post- clinical stages, we identified 15 previously unreported differentially expressed genes related to inflammation or activation of the STAT signal transductionpathway. Levels for the majority of differentially expressed genes increased with time postinfection. In quantitative immunoblotting experiments of STAT proteins, STAT1␣, phosphorylated-STAT1␣ (pSTAT1␣), and pSTAT3 were increased between 94 and 131 days postinfection (p.i.) in brains of mice infected with strain 22L. Furthermore, a select group of STAT-associated genes was increased preclinically during scrapie infection, suggesting early activation of the STAT signal trans- duction pathway. Comparison of inflammatory markers between mice infected with scrapie strains 22L and RML indicated that the inflammatory responses and gene expression profiles in the brains were strikingly similar, even though these scrapie strains infect different brain regions. The endogenous interleukin-1 receptor antagonist (IL-1Ra), an inflammatory marker, was newly identified as increasing preclinically in our model and therefore might influence scrapie pathogenesis in vivo. However, in IL- 1Ra-deficient or overexpressor transgenic mice inoculated with scrapie, neither loss nor overexpression of IL-1Ra demonstrated any observable effect on gliosis, protease-resistant prion protein (PrPres) formation, disease tempo, pathology, or expression of the inflammatory genes analyzed.
Methods: To examine the differentially expressed pro ﬁ les of lncRNAs and mRNAs using microarray analysis, we collected 15 specimens: ﬁ ve HBV-associated HCC tissues, ﬁ ve paired adjacent peritumoral liver tissues (APLT), and ﬁ ve distant peritumoral liver tissues (DPLT). Then, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to predict the biological roles and potential signaling pathways of these dysregulated mRNAs. In addition, lncRNA-mRNA co-expression network and signal transductionpathway network (Signal-net) were employed to further explore the potential target genes and roles of dysregulated lncRNAs in HBV-HCC pathogenesis. Finally, quantitative real-time PCR (qRT-PCR) was used to con ﬁ rm the expression of six selected dysregulated lncRNAs.