Yeast response to the DNA damaging beta-lapachone
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ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae
SUBMITTER: Jose Gadea
PROVIDER: E-GEOD-15412 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:β-lapachone (b-lap) is an anticancer agent that selectively induces cell death in human cancer cells. A mechanism for b-lap cytotoxicity was shown to be mediated by the NQO1 NAD(P)H dehydrogenase and radical oxygen species (ROS) generation in several tumour cells. To further characterise the molecular effects of b-lap action, we compared the gene expression profile of yeast cells treated or not with b-lap using cDNA microarrays. Genes involved in tolerance to oxidative stress were enriched in the set of differentially expressed genes. Accordingly, b-lap treatment generated reactive oxygen species (ROS), which were efficiently blocked by dicoumarol, and inhibitor of NADH dehydrogenases (NADH-DH). In addition, a mutant defective in the mitocondrial NADH dehydrogenase Nde2p was found to be resistant to b-lap treatment, thus resembling tumour cell responses to b-lap exposure. However, b-lap treatment elicited similar ROS production in WT and nde2 cells, and dicoumarol did not affect cell viability in b-lap treated yeasts. Most interestingly, DNA damage responses triggered by b-lap were abolished in the nde2 mutant. Furthermore, the nde2 mutant was sensitive to DNA damaging agents other than b-lap. These data indicated that ROS production did not mediate b-lap cytotoxicity and highlighted a role of Nde2p in DNA damage checkpoints. Amino acid biosynthesis genes were also differentially expressed in b-lap treated cells, suggesting that b-lap exposure somehow triggered the General Control of Nutrients (GCN) pathway. Supporting this, b-lap treatment increased phosphorylation of eIF2 alpha in a Gcn2p-dependent manner. eIF2alpha phosphorylation required Gcn1p and Gcn20p and surprisingly Nde2p. Gcn2p was also shown to be required for the G1 checkpoint triggered by b-lap and for cell survival. Remarkably, b-lap treatment also increased phosphorylation of eIF2 alpha in breast tumour cells, which was partially dependent on the Nde2p orthologue AMID. These findings i) suggest that Gcn2p and Nde2p are key determinants of b-lap toxicity in yeast and human cells, ii) uncover a new functional connection between Nde2p, Gcn2p and DNA damage checkpoints conserved throughout evolution and iii) suggest that pharmacological modulation of Gcn2p could provide an effective strategy for antitumour drug discovery.
2011-12-31 | GSE15412 | GEO
Project description:Regulation of gene expression by reactive oxygen species (ROS) is an important component of abiotic stress signal transduction mechanisms. Previous genome-wide analysis of chilling-induced changes in gene expression suggested a potential role of H2O2 and other ROS as key signals in the induction of early response genes in japonica rice (cv. Nipponbare). Candidate regulators including bZIP-, Myb- or WRKY-types of transcription factors that were responsive to both chilling (10oC) and exogenous H2O2, and their probable target clusters (as1/ocs/TGA1-like, MybR-like element containing genes) were inferred by integrative analysis of qPCR expression profiles and ab initio promoter motif data. In an effort to define the composition and hierarchical organization of the ROS-mediated chilling response regulatory networks, we examined the effect of exogenous H2O2 (6 hours in 4mM H2O2 at 28oC and then 6 hours of recovery in water at 28oC) on the transcriptome of Nipponbare in a genome-wide scale and compared them with the chilling stress transcriptome. Results of this study were consistent with our earlier model that a ROSbZIP-as1/ocs/TGA1 regulatory module is a direct consequence of chilling-induced elevation of intracellular ROS during the initial 24 hours. Keywords: time course (response to exogenous H2O2) This experiment describes the analysis of the temporal changes in gene expression in response to exogenous H2O2 in Nipponbare rice. A total of 5 treatment regimes were examined (1, 3, and 6 hours at 4 mM H2O2 and then 3 and 6 hours of recovery in water after 6 hours of exposure to H2O2). The microarray platform used in this study was the 45K oligonucleotide microarray (www.ricearray.org) which comes in pairs of slides A and B (each containing about 50% of the total number of features). The data described in this series include all hybridizations with slide A and with slide B. All experiments were performed with two independent biological replicates (R1 and R2) for each time point.
2010-06-24 | E-GEOD-10062 | biostudies-arrayexpress
Project description:rs10-02_ros_dme - genes regulated by ros and dme - Genes regulated by ros/dme? - Seeds of Col x ROS-/-/DME+/- 3 and 6 days after pollination (DAP) were harvested. Seeds of the cross Col x Col (3 and 6 DAP) were used as a control. 4 dye-swap - gene knock out
2011-06-01 | E-GEOD-29626 | biostudies-arrayexpress
Project description:The central role of transcriptional regulation in integrating various low temperature response mechanisms has been established in Arabidopsis, where the CBF/DREB regulon plays a prominent role during acclimation. Rice is sensitive to chilling but many japonica cultivars can survive continuous exposure to as low as 10oC for up to 7 days during the most critical stage of seedling establishment better than most indica cultivars. The transcriptional regulatory networks that define this variation have not been studied in detail as cold acclimation has been scrutinized in Arabidopsis. Towards the comparison of the compositional complexity of low temperature response regulons of rice and Arabidopsis, we used the cultivar Nipponbare for genome-wide survey of regulatory clusters by integrative analysis of promoter architectures and temporal expression profiles during exposure to 10oC at narrow time intervals. Temporal profiles revealed major clusters of genes that were induced within the initial 24 hours. These clusters were further defined by common features of having either CRT/DRE-like elements, as1/ocs-like elements or both in their promoters. Genes containing as1/ocs-like elements with or without CRT/DRE, but not those containing only CRT/DRE-like elements were induced by exogenous H2O2 but not by ABA at ambient temperature, suggesting that they belong to a potential regulon (ROS-bZIP – as1/ocs module) that responds to elevated levels of reactive oxygen species (ROS) during the initial stages of stress. Parallel analysis of transcription factors during the initial 12 hours revealed candidate regulator(s) of this putative early response regulon. Cultivar-specific expression signatures of selected members of this regulatory cluster were also positively correlated with genotypic variation in chilling tolerance. We hypothesized that the ROS-bZIP – as1/ocs cluster has important roles in configuring the transcriptome of rice seedlings during the early stages of chilling stress and it appears to be independent of ABA and functions in parallel to the CBF/DREB regulon. Keywords: time course (response to low temperature) This experiment describes the analysis of the temporal changes in gene expression in response to chilling temperature in Nipponbare rice. A total of 10 stress time points, i.e., 0.5, 2, 4, 6, 12, 18, 24, 36, 48, and 96 hrs after exposure to 10C in a growth chamber and one recovery time point, i.e., 96 hrs at 10C and then 24 hrs (24R) at ambient or control temperature (29C), were profiled with reference to a corresponding control, which was exposed to ambient temperature (29C) for the same length of time under cold stress (each stress time point has a corresponding control sample). Control and cold stress samples were labeled with Cy5 and Cy3, respectively. No dye swap replicate was performed in this experiment. The microarray platform used in this study was the 45K oligonucleotide microarray (www.ricearray.org) which comes in pairs of slides A and B (each containing about 50% of the total number of features). The data described in this series include all hybridizations with slide A and with slide B. All experiments were performed with two independent biological replicates (R1 and R2) for each time point.
2009-12-30 | E-GEOD-8767 | biostudies-arrayexpress
Project description:Development of mammary secretory epithelium and its functional differentiation occur during pregnancy under combined actions of ovarian steroids, pituitary hormones and growth factors. If the effect of these molecules is relatively well known, effect of differentiation factors expressed locally is not enough characterized. To understand local regulation of mammary tissue development and differentiation we realized transcriptional analysis on 5 physiological stages (4 during pregnancy and 1 during lactation). An appropriate experimental design was drawn to follow gene expression profiles during differentiation of mammary tissue. Results showed that at mid-pregnancy, mammary tissue was enough defferentiated into secretory epithelium to express milk protein genes and genes of the immune response system actors. But the secretoty activation of mammary epithelium was done only after parturition and wwas characterized by the expression of lipidogenesis genes. Keywords: time course, mammary gland differentiation, goat, pregnancy 18 samples, loop design
2010-05-16 | E-GEOD-14008 | biostudies-arrayexpress
Project description:Primary mediastinal B-cell lymphoma (PMBCL) is a distinct subtype of diffuse large B-cell lymphoma. PMBCL has been previously studied with a variety of genomic techniques resulting in frequent detection of chromosomal gains; however, chromosomal losses have been rarely reported. This finding contrasts many other types of lymphoma, in which deletions are common. We hypothesize that segmental losses do exist but may have escaped detection by methods used in the previous studies. Using array comparative genomic hybridization to a tiling-resolution microarray encompassing the entire human genome, PMBCL samples were analyzed for genomic copy number alterations. Both gains and losses of chromosomal material were detected throughout the genome. These DNA copy number alterations were confirmed by quantitative real-time PCR. Recurrent chromosomal losses include a novel event at 1p13.1-p13.2 present in 42% of cases analyzed. We conclude that losses are present in the PMBCL genome. Given the similar frequency of losses to that of segmental gains of DNA, they are likely to play an important role in the pathogenesis of PMBCL. Whole genome tiling path array CGH of 20 PMBCL tumor samples and one cell line was performed against male reference genomic DNA. Alterations were confirmed via DNA copy number quantitative real-time PCR
2007-08-15 | E-GEOD-7383 | biostudies-arrayexpress
Project description:In this study, we examined the very early transcriptional response of aposymbiotic coral larval host (still not engaged in symbiosis) to hyperthermal stress. This experimental setting provided a scenario and opportunity to study the direct effect of environmental stressors on the host cell per se. Using a cDNA microarray constructed for Acropora millepora and Q-RT-PCR assays, we identified a number of genes that were significantly up- and down-regulated with increase of seawater temperature. Down-regulation of several key component of DNA/RNA metabolism was detected implying inhibition of this cellular metabolic process, however the down-regulation of overall protein synthesis was not simple and random, which suggest that the response to stress is a more complicated adjustment to the metabolic needs of the cell. We identified four significant outcomes during the very early hours of the transcriptional response to hyperthermal stress in coral larvae. First, molecular chaperones responded to hyperthermal stress by increasing their expression as expected, but the response was immediate and extremely rapid during the first 3 hours of heat exposure. Secondly, elevated temperature triggers down-regulation of a fluorescent protein homolog, DsRed-type FP, suggesting that this gene might be used as a potential molecular marker for monitoring hyperthermal stress in nature. Thirdly, the downregulation of a coral mannose-binding lectin under hyperthermal stress might compromise the coral immune defense and bring about susceptibility to pathogenic diseases. And lastly, an absence in the response of oxidative stress genes in aposymbiotic coral larvae during the early hours to hyperthermal stress suggest that the up-regulation of cnidarian host oxidative stress genes reported during thermal stress in algal/host symbiosis might be triggered directly by ROS generated by photosynthetic-dysfunctionally algal endosymbionts that diffuse into host cells, as very little ROS seems to be produced by the host cells from thermal-associated host cellular damage. We applied a reference microarray design for the multi-factorial experiment outlined in the study, including two factors: Temperature (3 levels: 24 ËC, 28 ËC, 31 ËC) and Time (2 levels: 3h and 10h). Samples from time zero were used to generate the reference sample for the microarray hybridization experiments. A total of 18 microarrays were used in the entire experiment. Reference samples in each array was labeled with Cy3, and the actual experimenatl samples with Cy5. Ratio-Intensity plots were constructed for each array data to explore whether or not intensity dependence of log ratios, which appears as curvature, was present. Because curvatures were detected in a few of the arrays, an rLowess curve fitting transformation was applied to the data. The transformation was applied to all the arrays to keep consistence in the whole data. Quantile normalisation was also applied to mean log-intensities in order to make the distributions essentially the same across arrays. To detect differentially expressed genes among treatment through the course time of the experiment, a 2-way ANOVA model was fitted to the log transformed intensity data using the microarray analysis software GeneSpring (Agilent Technology). To correct for Type I error derived from multiple testing, the Benjamini and Hochberg method was applied as a false discovery rate (FDR) approach.
2010-10-08 | E-GEOD-16351 | biostudies-arrayexpress
Project description:Ferric uptake regulator (Fur) is the major regulator of iron acquisition in Escherichia coli and other bacteria. In the present study, the role of Fur in anaerobic S. enterica serovar Typhimurium was determined by transcriptome analysis, reporter assays, and enzymatic assays. In anaerobic ?fur, 298 genes were differentially expressed. In general, Fur repressed genes required for iron acquisition/storage, metabolism, electron transport, oxidative/nitrosative stress, and modulators of virulence. There were 73 genes whose expression required Fur, eleven of which contain a putative Fur box 5? of the gene. Transcription of sodA was >9-fold higher in ?fur but there was no corresponding increase in the activity of SodA. Anaerobic cultures of the fur mutant and the WT were used to inoculate two sets of three independent flasks each containing 150 ml of anoxic LB-MOPS-X. The three independent cultures were grown to an optical density at 600 nm (OD600) of 0.25 to 0.35, pooled, and treated with RNAlater (QIAGEN, Valencia, CA) to fix the cells and preserve the quality of the RNA. Total RNA was extracted with the RNeasy RNA extraction kit (QIAGEN), and the samples were treated with RNase-free DNase (Invitrogen, Carlsbad, CA). The absence of contaminating DNA and the quality of the RNA was confirmed by PCR amplification of known genes and by using agarose gel electrophoresis. Aliquots of the RNA samples were kept at –80°C for use in the microarray and quantitative real-time reverse transcription-PCR (qRT-PCR) studies. The SuperScript Indirect cDNA labeling system (Invitrogen) was used to synthesize the cDNA for the hybridizations. Each experiment consisted of two hybridizations, on two slides, and was carried out in Corning Hybridization Chambers at 42°C overnight. Dye swapping was performed to avoid dye-associated effects on cDNA synthesis. The slides were washed at increasing stringencies (2x SSC [1x SSC is 0.15 M NaCl plus 0.015 M sodium citrate], 0.1% sodium dodecyl sulfate [SDS], 42°C; 0.1% SSC, 0.1% SDS, room temperature; 0.1% SSC, room temperature). Following hybridization, the microarrays were scanned for the Cy3 and Cy5 fluorescent signals with a ScanArray 4000 microarray scanner from GSI Lumonics (Watertown, MA). The intensity of every spot was codified as the sum of the intensities of all the pixels within a circle positioned over the spot itself and the background as the sum of the intensities of an identical number of pixels in the immediate surroundings of the circled spot. Cy3 and Cy5 values for each spot were normalized over the total intensity for each dye to account for differences in total intensity between the two scanned images. The consistency of the data obtained from the microarray analysis was evaluated by a pair-wise comparison, calculated with a two-tailed Student's t test and analyzed by the MEAN and TTEST procedures of SAS-STAT statistical software (SAS Institute, Cary, NC) . The signal intensity at each spot from the fur mutant and the WT were background subtracted, normalized, and used to calculate the ratio of gene expression between the two strains. All replicas were combined, and the median expression ratios and standard deviations were calculated for open reading frames (ORFs) showing 2.5-fold change.
2011-10-13 | E-GEOD-18441 | biostudies-arrayexpress
Project description:Spot intensity serves as a proxy for gene expression in dual-label microarray experiments. Dye bias is defined as an intensity difference between samples labeled with different dyes attributable to the dyes instead of the gene expression in the samples. Dye bias that is not removed by array normalization can introduce bias into comparisons between samples of interest. But if the bias is consistent across the samples for the same gene, it can be corrected by proper experimental design and analysis. If the dye bias is not consistent across samples for the same gene, but is different for different samples, then removing the bias becomes more problematic, perhaps indicating a technical limitation to the ability of fluorescent signals to accurately represent gene expression. Thus, it is important to characterize dye bias to determine: (1) whether it will be removed for all genes by array normalization, (2) whether it will not be removed by normalization but can be removed by proper experimental design and analysis and (3) whether dye bias correction is more problematic than either of these and is not easily removable. For two dual-label experiments, one with cDNA arrays and the other with printed oligonucleotide arrays, Stratagene universal human reference RNA was used as a standard for testing with RNA from cell lines MCF10a, LNCAP, L428, SUDHL, OCILY3 and Jurkat. All arrays were dye-swapped at least twice. There were a total of 28 cDNA arrays and 30 oligonucleotide arrays.
2006-06-06 | E-GEOD-4982 | biostudies-arrayexpress
Project description:Juvenile gilthead sea bream of 10-15 g initial body weight were randomly distributed in eight 500-L tanks in a seawater re-circulatory system equipped with physical and biological filters, and a heat-unit system that maintained water temperature above 18-19 ºC. Fish grew from July to December at a density of 8-10 kg/m3 with an overall daily growth index of 1.9 ± 0.01. Extruded pellets (47 % protein, 21% lipid; Proaqua, Palencia, Spain) were offered to visual satiety. Feeding was stopped one day before confinement exposure, and batches of 10 fish were then transferred from two 500-L tanks to cylinder net baskets of 10-L volume (117-123 Kg/m3), suspended each one in 90-L tanks with a high flow of seawater (10 L/min) to avoid water deterioration (Oxygen > 5 ppm; unionised ammonia < 0.02 mg/L). Fish from seven additional 500-L tanks were established as control groups, and remained undisturbed prior to sampling at zero and each sampling time. At each sampling time (1.5, 3, 6, 24, 72 and 120 h), eight fish from one control and one confinement tank were netted into a bucket to be anaesthetized with 0.1 g/L 3-aminobenzoic acid ethyl ester (MS-222). Fish were killed by cervical section and liver was taken, frozen immediately in liquid nitrogen and stored at -80 ºC until RNA isolation. Only 6h, 72h and 120h were analysed on the microarray. The experimental design was a reference design with the reference being prepared from a pool of all (confined and control) RNAs used in the microarray analysis. All samples were hybridised twice (except L72C5R, L120C2F, L120S4F, L24C4F) with one being the dye swap of the other. Keywords: Time Course 72 samples
2010-06-24 | E-GEOD-16633 | biostudies-arrayexpress