Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

The association between gene expression and whole genome histone H3K4 mono-, di, and trimethylation: expression data

ABSTRACT: These microarrays are part of a study where a comparison was made between the change in transcription and H3K4 mono-, di-, and tri-methylation levels (via ChIP-seq) in the Arabidopsis thaliana genome when plants are subjected to water deficit stress. Water deficit stress causes a large number of genes to change their transcript levels, which provided a large set of genes to examine for corresponding chromatine changes. Keywords: stress response Arabidopsis thaliana RNA was isolated from control (watered) and treatment (water-deficit) samples for analysis on microarrays with three biological reps.

ORGANISM(S): Arabidopsis thaliana

SUBMITTER: Jean-Jack Riethoven

PROVIDER: E-GEOD-11538 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Dynamic changes in genome-wide histone H3 lysine 4 methylation patterns in response to dehydration stress in Arabidopsis thaliana.

van Dijk Karin K Ding Yong Y Malkaram Sridhar S Riethoven Jean-Jack M JJ Liu Rong R Yang Jingyi J Laczko Peter P Chen Han H Xia Yuannan Y Ladunga Istvan I Avramova Zoya Z Fromm Michael M

BMC plant biology 20101105

<h4>Background</h4>The molecular mechanisms of genome reprogramming during transcriptional responses to stress are associated with specific chromatin modifications. Available data, however, describe histone modifications only at individual plant genes induced by stress. We have no knowledge of chromatin modifications taking place at genes whose transcription has been down-regulated or on the genome-wide chromatin modification patterns that occur during the plant's response to dehydration stress. ...[more]

PMID: 21050490

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Project description:Previous work showed that the maize primary root adapts to low water potential (-1.6 MPa) by maintaining longitudinal expansion in the apical 3 mm (region 1), whereas in the adjacent 4 mm (region 2) longitudinal expansion reaches a maximum in well-watered roots but is progressively inhibited at low water potential. To identify mechanisms that determine these responses to low water potential, transcript expression was profiled in these regions of water-stressed and well-watered roots. In addition, comparison between region 2 of water-stressed roots and the zone of growth deceleration in well-watered roots (region 3) distinguished stress-responsive genes in region 2 from those involved in cell maturation. Responses of gene expression to water stress in regions 1 and 2 were largely distinct. The largest functional categories of differentially expressed transcripts were reactive oxygen species and carbon metabolism in region 1, and membrane transport in region 2. Transcripts controlling sucrose hydrolysis distinguished well-watered and water-stressed states (invertase vs. sucrose synthase), and changes in expression of transcripts for starch synthesis indicated further alteration in carbon metabolism under water deficit. A role for inositols in the stress response was suggested, as was control of proline metabolism. Increased expression of transcripts for wall-loosening proteins in region 1, and for elements of ABA and ethylene signaling were also indicated in the response to water deficit. The analysis indicates that fundamentally different signaling and metabolic response mechanisms are involved in the response to water stress in different regions of the maize primary root elongation zone. Keywords: water stress response, root growth Three pair-wise comparisons were made of transcripts from water-stressed and well-watered tissues in the different root tip regions. In the first comparison (C1), transcripts from region 1 of water-stressed seedlings were compared with those from region 1 of well-watered seedlings. The second comparison (C2) was made between transcripts from region 2 of the two treatments. We expected a larger number of genes to be differentially expressed in region 2 because its elongation rate decreased greatly under water-stressed compared with well-watered conditions. To prioritize the differentially expressed genes revealed in this comparison, a distinction was made between those genes that are associated with growth inhibition in region 2 specifically as a response to water stress, and those genes that are involved in root cell maturation whether under stress or control conditions. A hypothetical example of the former might be genes involved in auxin response since water stress can increase maize root auxin content [8] and application of exogenous auxin can shorten the root growth zone [9]. An example of the latter might involve genes for secondary wall synthesis, e.g., [10]. To experimentally make this distinction a third pair-wise comparison (C2/3) was included to compare expression of genes between water-stressed region 2 and well-watered region 3 as these are both regions of cell maturation. Genes differentially expressed in both C2 and C2/3 are more likely to cause growth inhibition at low water potential and are not likely to be part of the maturation program itself, whereas genes differentially expressed only in C2 are more likely related to maturation. Four biological replicates were included each with dye-swap. The maize oligonucleotide array comes in two slides, A and B. Thus for each of the three comparisons made there were 16 slides (4 biological reps, 2 for dye-swap, 2 parts to an array).

Project description:Background Housekeeping genes (HKG) are constitutively expressed in all tissues while tissue-enriched genes (TEG) are expressed at a much higher level in a single tissue type than in others. HKGs serve as valuable experimental controls in gene and protein expression experiments, while TEGs tend to represent distinct physiological processes and are frequently candidates for biomarkers or drug targets. The genomic features of these two groups of genes expressed in opposing patterns may shed light on the mechanisms by which cells maintain basic and tissue-specific functions. Results Here, we generate gene expression profiles of 42 normal human tissues on custom high-density microarrays to systematically identify 1,522 HKGs and 975 TEGs and compile a small subset of 20 housekeeping genes that can be used as experimental reference and are superior to many commonly used HKGs. Cross-species comparison shows that both the functions and expression patterns of HKGs are conserved. TEGs are enriched with respect to both segmental duplication and copy number variation, while no such enrichment is observed for HKGs, suggesting the high expression of HKGs are not due to high copy numbers. Analysis of genomic and epigenetic features of HKGs and TEGs reveals that the high expression of HKGs across different tissues is associated with decreased nucleosome occupancy at the transcription start site as indicated by enhanced DNase hypersensitivity. Additionally, we systematically and quantitatively demonstrated that the CpG islands' enrichment in HKGs transcription start sites (TSS) and their depletion in TEGs TSS. Histone methylation patterns differ significantly between HKGs and TEGs, suggesting that methylation contributes to the differential expression patterns as well. Conclusions We have compiled a set of high quality HKGs that should provide higher and more consistent expression when used as references in laboratory experiments than currently used HKGs. The comparison of genomic features between HKGs and TEGs shows that HKGs are more conserved than TEGs in terms of functions, expression pattern and polymorphisms. In addition, our results identify chromatin structure and epigenetic features of HKGs and TEGs that are likely to play an important role in regulating their strikingly different expression patterns. PolyA+ purified RNA pooled from multiple donors of a single human tissue type (e.g. cerebellum) were amplified with random primers and hybridized on a two-color ink-jet oligonucletodie microarray against a common reference pool, comprising ~20 normal adult tissue pools, on custom microarray patterns. Total 42 normal human tissues were testes against the pools. This dataset is part of the TransQST collection.

Dataset Information

The association between gene expression and whole genome histone H3K4 mono-, di, and trimethylation: expression data

Publications

Dynamic changes in genome-wide histone H3 lysine 4 methylation patterns in response to dehydration stress in Arabidopsis thaliana.

Similar Datasets

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