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GSE49918
Escherichia coli
12 Downloadable Samples
Affymetrix E. coli Genome 2.0 Array (ecoli2)
Description
As part of our studies on the biological functions of polyamines we have used a mutant of Escherichia coli that lacks all the genes for polyamine biosynthesis for a global transcription analysis on the effect of added polyamines. The most striking early response to polyamine addition is the increased expression of the genes for the glutamate dependent acid resistance system (GDAR) that is essential for the survival of bacteria when passing through the acid environment of the stomach. Not only were the two genes for glutamate decarboxylases (gadA and gadB) and the gene for glutamate --aminobutyrate antiporter (gadC) induced by polyamine addition, but also the various genes involved in the regulation of this system were induced. We confirmed the importance of polyamines for the induction of the GDAR system by direct measurement of glutamate decarboxylase activity and acid-survival. Effects of deletions of the regulatory genes in the GDAR system and on the effects of overproduction of two of these genes were also studied. Strikingly, overproductions of the alternate sigma factor rpoS and of the regulatory gene gadE resulted in very high levels of glutamate decarboxylase and almost complete protection against acid stress even in the absence of any polyamines. Thus, these data show that a major function of polyamines in E. coli is protection against acid stress by increasing the synthesis of glutamate decarboxylase, presumably by increasing the levels of the rpoS and gadE regulators.
Publication Title
Polyamines are critical for the induction of the glutamate decarboxylase-dependent acid resistance system in Escherichia coli.
Sample Metadata Fields
Treatment
View Samples- Escherichia coli
- 6 Downloadable Samples
- Affymetrix E. coli Genome 2.0 Array (ecoli2)
Description
Glutathionylspermdine synthetase/amidase (Gss) and the encoding gene (gss) have only been described in two widely separated species; namely Escherichia coli and several members of the Kinetoplastida phyla. In the present paper we have studied the species distribution more extensively. It is striking that all of the 75 Enterobacteria species that has been sequenced contain sequences with very high degree of homology to the E. coli Gss protein. Although homologous sequences are also present in various other bacteria, in contrast to Enterobacteria they are not present in all species of a given phyla. As previously reported homologous sequences were found in all five species of Kinetoplastids tested (including Trypansosma cruzi), but it is striking that comparable sequences are not found in a variety of invertebrate and vertebrate species, Archea and plants. Studies in E. coli show that the highest accumulation of glutathionylspermidine is found in stationary phase cultures where most of the intracellular spermidine is converted to glutathionylspermidine. However, even in log phase cells there is some formation of glutathionylspermidine, and isotope exchange experiments show that there is a rapid exchange between glutathionylspermidine and intracellular spermidine. We have not been able to define a specific physiologic function for glutathionylspermidine, but microarray studies comparing gss+ and -gss strains of E. coli show that a large number of genes are either upregulated or downregulated by the loss of the gss gene.
Publication Title
Escherichia coli glutathionylspermidine synthetase/amidase: phylogeny and effect on regulation of gene expression.
Sample Metadata Fields
No sample metadata fields
View Samples- Escherichia coli
- 24 Downloadable Samples
- Affymetrix E. coli Genome 2.0 Array (ecoli2)
Description
To study the physiological roles of polyamines, we have carried out a global microarray analysis on the effect of adding polyamines to an Escherichia coli mutant that lacks polyamines because of deletions in the genes in the polyamine biosynthetic pathway. Previously, we have reported that the earliest response to the polyamine addition is the increased expression of the genes for the glutamate dependent acid resistance system (GDAR). We also presented preliminary evidence for the involvement of rpoS and gadE regulators. In the current study further confirmation of the regulatory roles of rpoS and gadE is shown by a comparison of genome-wide expression profiling data from a series of microarrays comparing the genes induced by polyamine addition to polyamine-free rpoS+/gadE+ cells with genes induced by polyamine addition to polyamine-free rpoS and gadE cells. The results indicate that most of the genes in the E. coli GDAR system that are induced by polyamines require rpoS and gadE. Our data also show that, gadE is the main regulator of GDAR and other acid-fitness-island genes. Both polyamines and rpoS are necessary for the expression of gadE genes from the three promoters of gadE (P1, P2 and P3). The most important effect of polyamine addition is the very rapid post-transcriptional increase in the level of RpoS sigma factor. Our current hypothesis is that polyamines increase the level of RpoS protein, and that this increased RpoS level is responsible for the stimulation of gadE expression, which in turn induces the GDAR system in E. coli.
Publication Title
Polyamines Stimulate the Level of the σ38 Subunit (RpoS) of Escherichia coli RNA Polymerase, Resulting in the Induction of the Glutamate Decarboxylase-dependent Acid Response System via the gadE Regulon.
Sample Metadata Fields
Treatment
View Samples- Arabidopsis thaliana
- 8 Downloadable Samples
- Affymetrix Arabidopsis ATH1 Genome Array (ath1121501)
Description
Three bZIP transcription factors (TFs), namely GBF1, HY5, and HYH, form heterodimers with each other and regulate photomorphogenesis in an interdependent manner. GBF1 acts as both a positive and negative regulator of photomorphogenesis, whereas HY5 and HYH mainly act as positive regulators of photomorphogenesis. To study the effect of HY5 and HYH on GBF1-mediated genome-wide expression, transcript profiling was performed in the gbf1 single mutant and gbf1hy5 and gbf1hyh double mutants. Our study revealed that GBF1 mainly acts antagonistic to HY5 and HYH for genome-wide expression.
Publication Title
Genome-wide DNA binding of GBF1 is modulated by its heterodimerizing protein partners, HY5 and HYH.
Sample Metadata Fields
Age, Specimen part
View Samples- Arabidopsis thaliana
- 12 Downloadable Samples
- Affymetrix Arabidopsis ATH1 Genome Array (ath1121501)
Description
A chemical screen was performed in search of compounds that modify plant responses to sucrose. This screen uncovered that sulfamethoxazole (SMX), a folate biosynthesis inhibitor, acted synergistically with sucrose to inhibit hypocotyl elongation, suggesting interaction between these two pathways. Transcriptome analysis was performed to identify changes in transcript abundance that may underpin crosstalk between sucrose and SMX. Three-day-old dark-grown seedlings were treated to sucrose and SMX at concentrations that induced no change in hypocotyl elongation when administered independently, yet restricted elongation when both were present in the growth media (10mM and 0.2M, respectively). This analysis uncovered multiple core auxin signalling components that exhibit altered transcript abundance in response to co-treatment with sucrose and SMX, suggesting that auxin signalling mediates crosstalk between these two pathways. This study highlights an input through which metabolic status can shape plant growth and development through hormone signalling.
Publication Title
Interplay between sucrose and folate modulates auxin signaling in Arabidopsis.
Sample Metadata Fields
Specimen part
View Samples- Saccharomyces cerevisiae
- 13 Downloadable Samples
- Affymetrix Yeast Genome S98 Array (ygs98)
Description
The naturally occurring polyamines putrescine, spermidine or spermine are ubiquitous in all cells. Although polyamines have prominent regulatory roles in cell division and growth, precise molecular and cellular functions are not well established in vivo. In this work we have performed a microarray experiment in a polyamine mutant (delta-spe3 delta-fms1) strain to investigate the responsiveness of yeast genes to supplementation with spermidine and spermine. Expression analysis identified genes responsive to the addition of either excess spermidine (10-5 M) or spermine (10-5 M) compared to a control culture containing 10-8 M spermidine. 247 genes were up-regulated >2-fold, and 11 genes were up-regulated more than 10-fold after spermidine addition. Functional categorization of the genes showed induction of transport related genes, and genes involved in methionine, arginine, lysine, NAD and biotin biosynthesis. 268 genes were down-regulated more than 2-fold, and 6 genes were down-regulated more than 8-fold after spermidine addition. A majority of the down-regulated genes are involved in nucleic acid metabolism and various stress responses. In contrast, only few genes (18) were significantly responsive to spermine. Thus, results from global gene expression profiling demonstrate a more major role for spermidine in modulating gene expression in yeast than spermine.
Publication Title
Microarray studies on the genes responsive to the addition of spermidine or spermine to a Saccharomyces cerevisiae spermidine synthase mutant.
Sample Metadata Fields
Treatment
View Samples- Arabidopsis thaliana
- 18 Downloadable Samples
- Affymetrix Arabidopsis ATH1 Genome Array (ath1121501)
Description
Microarrays were used to evaluate the effect of sucrose on gene expression in guard cells. Strips of Arabidopsis leaves were incubated with sucrose or mannitol or no sugars, then the leaves were freeze dried and guard cells were dissected from the leaf strips and analyzed.
Publication Title
A comparative study of the Arabidopsis thaliana guard-cell transcriptome and its modulation by sucrose.
Sample Metadata Fields
Specimen part
View Samples- Mus musculus
- 14 Downloadable Samples
Illumina HiSeq 2500
Description
Adult hematopoiesis has been studied in terms of progenitor differentiation potentials, whereas its kinetics in vivo is poorly understood. We combined inducible lineage tracing of endogenous adult hematopoietic stem cells (HSC) with flow cytometry and single-cell RNA sequencing to characterize early steps of hematopoietic differentiation in the steady state. Labeled cells, comprising primarily long-term HSC and some short-term HSC, produced megakaryocytic lineage progeny within one week, in a process that required only 2-3 cell divisions. Erythroid and myeloid progeny emerged simultaneously by 2 weeks, and included a progenitor population with expression features of both lineages. Myeloid progenitors at this stage showed diversification into granulocytic, monocytic and dendritic cell types, and rare intermediate cell states could be detected. In contrast, lymphoid differentiation was virtually absent within the first 3 weeks of tracing. These results show that continuous differentiation of HSC rapidly produces major hematopoietic lineages and cell types, and reveal fundamental kinetic differences between megakaryocytic, erythroid, myeloid and lymphoid differentiation. Overall design: We combined inducible lineage tracing of endogenous adult hematopoietic stem cells (HSC) with flow cytometry and single-cell RNA sequencing to characterize early steps of hematopoietic differentiation in the steady state.
Publication Title
Kinetics of adult hematopoietic stem cell differentiation in vivo.
Sample Metadata Fields
Specimen part, Subject
View Samples- Homo sapiens
- 72 Downloadable Samples
- Illumina human-6 v2.0 expression beadchip
Description
The type II Oncostatin M receptor (OSMR) serves as the main binding site for the pleiotropic cytokine OSM. We have previously demonstrated a positive correlation between copy number driven OSMR over-expression and adverse clinical outcome in cervical tumours and have also established enhanced angiogenic, migratory and invasive potential as major consequences of OSMR over-expression using cell-line models of cervical cancer. By analysis of gene expression patterns in cell lines and tumours, this study now systematically defines cohorts of genes that are implicated for the phenotypes observed. Importantly, we have identified 15 OSM induced genes that are involved in at least one of these key functions and are up-regulated in both OSMR over-expressing cell-lines and tumours. These genes can serve as markers of OSM signalling in OSMR over-expressing SCCs and represent suitable targets for functional characterisation.
Publication Title
Overexpression of the oncostatin M receptor in cervical squamous cell carcinoma cells is associated with a pro-angiogenic phenotype and increased cell motility and invasiveness.
Sample Metadata Fields
Sex, Cell line, Time
View Samples- Mus musculus
- 24 Downloadable Samples
- Illumina HiSeq 2500
Description
For most multigenic disorders, clinical manifestation (penetrance) and presentation (expressivity) are likely to be an outcome of genetic interaction between multiple susceptibility genes. Here, using gene knockouts in mice we evaluated genetic interaction between loss of Ret and loss of Sema3d, two Hirschsprung disease (HSCR) susceptibility genes. We intercrossed Ret and Sema3d double null heterozygotes to generate mice with the nine possible genotypes and assessed survival by counting various genotypes, myenteric plexus development by acetylcholinesterase (AchE) staining and embryonic day 12.5 (E12.5) gut transcriptome by RNA-sequencing. Survival rates of Ret wildtype, null heterozygote and null homozygote mice at E12.5, birth and weaning were not influenced by the genotypes at Sema3d locus and vice-versa. Loss of myenteric plexus was observed only in all Ret null homozygotes, irrespective of the genotypes at Sema3d locus, and Sema3d null heterozygote and homozygote mice had normal gut innervation. As compared to wildtype mice gut gene expression, loss of Ret in null homozygotes led to differential expression of ~300 genes, whereas loss of Sema3d in null homozygotes had no major consequence and there was no evidence supporting major interaction between the two genes influencing gut transcriptome. Overall, given the null alleles and phenotypic assays used, we did not find evidence for genetic interaction between Ret and Sema3d affecting survival, myenteric plexus formation or gut transcriptome. Overall design: poly-A RNA-seq in embryonic day 12.5 mouse gut from 3 wildtype males, 3 wildtype females, 3 Ret null homozyogote males, 3 Ret null homozyogote females, 3 Sema3d null homozyogote males, 3 Sema3d null homozyogote females, 3 Ret-Sema3d double null homozyogote males, 3 Ret-Sema3d double null homozyogote females
Publication Title
Testing the Ret and Sema3d genetic interaction in mouse enteric nervous system development.
Sample Metadata Fields
Sex, Specimen part, Cell line, Subject
View Samples