Adenine effect on Enterohemorraghic E.coli
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ABSTRACT:
ORGANISM(S): Escherichia coli
PROVIDER: GSE244178 | GEO | 2024/05/01
REPOSITORIES: GEO
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Project description:Previous experiments have shown that E. feacalis increases EHEC virulence, this RNAseq aims to understand the molecular mechanism underlaying this phenotype
2024-03-01 | GSE226433 | GEO
Project description:Adenine effect on Enterohemorraghic E.coli
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Project description:EHEC is a food-borne pathogen that colonizes human GI tract and leads to infection. To understand the process of colonization and to decipher if any factors secreted by intestinal epithelial cells help EHEC during the infection process, we studied expression of EHEC virulence gene expression when exposed to intestinal epithelial cell conditioned medium. In our study, we observed that exposure to epithelial cell conditioned medium for 1 h and 3 h increases expression of 32 out of 41 EHEC LEE virulence genes. In addition, expression of the shiga toxin 1 (Stx1) gene is up-regulated at 1 h of exposure. Also, 17 genes encoded by prophage 933W, including those for Stx2, are also upregulated at both time-points. The increase in 933W prophage expression is mirrored by a 2.7-fold increase in intracellular Stx2 phage titers. Consistent with the increase in virulence gene expression, we observed a 5-fold increase in EHEC attachment to epithelial cells when exposed to conditioned medium, suggesting that EHEC utilizes host cell molecules to increase virulence and infectivity. The molecule(s) responsible for increased EHEC virulence is heat-sensitive as heating the conditioned medium to 95oC abolishes the increase in attachment to epithelial cells. A similar decrease was observed when the conditioned medium was treated with proteinase-K to degrade the proteins. The secreted molecule(s) was found to be larger than 3 kDa and strongly suggests that the HCT-8 secreted molecule that increases EHEC virulence and colonization is a protein-based molecule. Affymetrix E. coli Genome 2.0 Arrays were used to determine the changes in EHEC virulence gene expression on exposure to intestinal epithelial cell-secreted factors (through growth in conditioned medium).
2012-10-04 | GSE22285 | GEO
Project description:EHEC is a food-borne pathogen that colonizes human GI tract and leads to infection. To understand the process of colonization and to decipher if any factors secreted by intestinal epithelial cells help EHEC during the infection process, we studied expression of EHEC virulence gene expression when exposed to intestinal epithelial cell conditioned medium. In our study, we observed that exposure to epithelial cell conditioned medium for 1 h and 3 h increases expression of 32 out of 41 EHEC LEE virulence genes. In addition, expression of the shiga toxin 1 (Stx1) gene is up-regulated at 1 h of exposure. Also, 17 genes encoded by prophage 933W, including those for Stx2, are also upregulated at both time-points. The increase in 933W prophage expression is mirrored by a 2.7-fold increase in intracellular Stx2 phage titers. Consistent with the increase in virulence gene expression, we observed a 5-fold increase in EHEC attachment to epithelial cells when exposed to conditioned medium, suggesting that EHEC utilizes host cell molecules to increase virulence and infectivity. The molecule(s) responsible for increased EHEC virulence is heat-sensitive as heating the conditioned medium to 95oC abolishes the increase in attachment to epithelial cells. A similar decrease was observed when the conditioned medium was treated with proteinase-K to degrade the proteins. The secreted molecule(s) was found to be larger than 3 kDa and strongly suggests that the HCT-8 secreted molecule that increases EHEC virulence and colonization is a protein-based molecule. Affymetrix E. coli Genome 2.0 Arrays were used to determine the changes in EHEC virulence gene expression on exposure to intestinal epithelial cell-secreted factors (through growth in conditioned medium). Overnight cultures of EHEC were diluted in LB medium to a turbidity of 0.1 at 600 nm. The cells were allowed to grow to a turbidity of 1.0 at 600 nm at 37°C and the EHEC cells were then resuspended in either fresh or conditioned medium. The cultures were then allowed to grow for 1 h or 3 h before cell pellets were collected by centrifugation and stored at -80°C. Total RNA was isolated from the cell pellets (173) and RNA quality was assessed using gel electrophoresis. Escherichia coli Genome 2.0 arrays (Affymetrix, Santa Clara, CA, USA) containing 10,208 probe sets for all 20,366 genes present in four strains of E. coli, including EHEC, were used to profile changes in gene expression using RNA samples for each treatment.
2012-10-04 | E-GEOD-22285 | biostudies-arrayexpress
Project description:While significant advances have been made in EHEC pathogenesis, we still do not fully understand the impact of environmental stress on EHEC virulence. During the course of infection, EHEC must evade or overcome several biological barriers, the first of which is the gastric acidity encountered during passage through the stomach. EHEC is remarkable in its ability to tolerate this acidity. There are four different acid resistance systems that provide E. coli O157:H7 protection against exposure to low pH (2-2.5). Interestingly, EHEC uses these acid resistance systems differentially for survival in foods versus the bovine intestinal tract. The glutamate-dependent acid-resistance system is thought to offer the best protection below pH 3. Since the infectious dose of EHEC is so low (50-100 organisms), acid resistance becomes an important virulence trait. Studies of EHEC response to acid stress have focused primarily on levels of acid tolerance and the molecular basis of tolerance. However, the impact of acid stress on EHEC virulence is less well understood. In the related pathogen, EPEC, the plasmid-encoded regulator, Per, that regulates expression of many EPEC virulence factors, is regulated negatively at pH 5.5 and positively at pH 8.0, suggesting that virulence gene expression is repressed during mild acid stress and enhanced in alkaline pH typical of the small intestine. Expression of EPEC type III secreted factors involved in A/E lesion formation has been shown to be influenced by factors including culture media, iron and calcium levels. Protein secretion was inhibited at pH 6 and 8. In a third study, a gadE (encoding acid resistance regulator) mutation resulted in increased adhesion of E.coli O157:H7 to colonic epithelial cells, suggesting negative regulation of one or more adhesins. Other studies have reported that shiga toxin production is sensitive to culture conditions including pH. However, there are no studies of EHEC virulence changes after more severe acid stress nor studies linking stressed EHEC virulence phenotype with transcriptional changes. The goal of this study was to determine how acid stress affects EHEC virulence properties and through microarray analysis, define the genetic basis for these changes. Understanding how acid stress modulates the virulence potential of this pathogen is essential for delineating the pathogenesis of disease caused by EHEC infection and may offer novel approaches to prevent and treat EHEC infections.
2009-06-26 | GSE14069 | GEO
Project description:VS94 gene expression at different time-points in SAPI medium in absence and presence of AI-2 was studied. Autoinducer-2 (AI-2) is produced by many species of bacteria, including various commensal bacteria and is involved in inter-species communication. Since, pathogens encounter AI-2 once they enter the human gastro-intestinal tract; we studied the effects of presence of AI-2 on various phenotypes associated with infection and colonization of enterohemorrhagic Escherichia coli (EHEC) namely, chemotaxis, motility and attachment to HeLa cells. AI-2 attracted EHEC when observed in agarose plug assays and also increased EHEC motility by 1.44-fold. AI-2 also increased EHEC attachment to HeLa cells by 1.6-fold; hence, suggesting that exposure to AI-2 inside the gastro-intestinal tract can play an important role in EHEC colonization. We then investigated the global effects of AI-2 on EHEC gene expression using DNA microarrays at various time-points. We found that AI-2 controls virulence gene expression and several other groups of genes (flagellar genes, iron related genes, biofilm genes etc.) associated with virulence in a time-dependent manner. Hence, through these studies we have shown that AI-2 may be a key component in EHEC infection of human gastro-intestinal tract. Experiment Overall Design: Strain: VS94 (EHEC luxS mutant) Experiment Overall Design: Medium: SAPI Experiment Overall Design: Temperature: 37C Experiment Overall Design: Cell type: Suspension Experiment Overall Design: Chemical: 100 uM AI-2 Experiment Overall Design: Overnight cultures of VS94 were diluted in SAPI medium to a turbidity of 0.1. The cells were allowed to grow to a turbidity of 0.5 at 37 oC and 100 µM AI-2 was added to the culture. In the control flasks, no AI-2 was added. The cultures were then allowed to grow for further 3.5 hours, 4 hours, 4.5 hours and 5.5 hours before cell pellets were collected by centrifugation at the above mentioned time-points and stored at -80oC. Experiment Overall Design: Total RNA was isolated from isolated cell pellets and RNA quality was assessed using gel electrophoresis. E. coli Genome 2.0 arrays (Affymetrix, California) containing 10,208 probe sets for all 20,366 genes present in four strains of E. coli, including E. coli O157:H7, were used to profile changes in gene expression using RNA samples for each treatment. Hybridization was performed for 16 hours, and the total cell intensity was scaled automatically in the software to an average value of 500. The data were inspected for quality and analyzed according to the procedures described by the manufacturer (Affymetrix: Data Analysis Fundamentals) which include using premixed polyadenylated transcripts of the B. subtilis genes (lys, phe, thr, and dap) at different concentrations. Genes were identified as differentially expressed if the expression ratio (between AI-2 and control cells at different time-points) was greater than 1.5 (based on the standard deviation between values measuring relative changes in expression) (Ren et al. 2004) and the change in the P value was less than 0.05. The differentially expressed genes were annotated using gene ontology definitions available in the Affymetrix NetAffx Analysis Center (http://www.affymetrix.com/analysis/index.affx).
2008-04-04 | E-GEOD-9388 | biostudies-arrayexpress
Project description:In mammalian cells, DNA methylation on the 5th position of cytosine (5mC) plays an important role as an epigenetic mark. However, DNA methylation was considered to be absent in C. elegans because of the lack of detectable 5mC as well as homologs of the cytosine DNA methyltransferases. Here, using multiple approaches, we demonstrate the presence of adenine N6-methylation (6mA) in C. elegans DNA. We further demonstrate that this modification increases trans-generationally in a paradigm of epigenetic inheritance. Importantly, we identify a DNA demethylase, NMAD-1, and a potential DNA methyltransferase, DAMT-1, which regulate 6mA levels and crosstalk between methylation of histone H3K4me2 and 6mA, and control the epigenetic inheritance of phenotypes associated with the loss of the H3K4me2 demethylase spr-5. Together, these data identify a novel DNA modification in C. elegans and raise the exciting possibility that 6mA may be a carrier of heritable epigenetic information in eukaryotes. SMRT-sequencing for a mixed cell population of wildtype worms 6mA ChIP-Seq for a mixed cell population of wildtype worms
2015-05-05 | E-GEOD-66504 | biostudies-arrayexpress
Project description:In previous study, we demonstrated adenine-induced cell signaling on anti-inflammation in BV2 cells. To investigate the changes of transcriptome mediated by adenine, we used microarrays to compare the difference in expression levels.
2017-08-01 | GSE84217 | GEO
Project description:Time course of Arabidopsis seedlings treated with 6-Benzyl adenine dissolved in diluted KOH for 15 min or 2 hours
2008-06-11 | E-GEOD-1766 | biostudies-arrayexpress
Project description:Comparative genome sequencing of E.coli EHEC isolated from an outbreak
| PRJEB588 | ENA