Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

ChIP-seq to identify the positions of three histone modifications in the rice genome

ABSTRACT: Gene expression is controlled by the complex interaction of transcription factors binding to promoters and other regulatory DNA elements. One common characteristic of the genomic regions associated with regulatory proteins is a pronounced sensitivity to DNase I digestion. We generated genome-wide high resolution maps of DNase I hypersensitive (DH) sites from both seedling and callus tissues of rice. Approximately 25% of the DH sites from both tissues were found in the putative promoters, indicating that the vast majority of gene regulatory elements in rice are not located at promoter regions. We found 58% more DH sites in callus than in seedling. For DH sites detected in both seedling and callus, 31% displayed significantly different levels of DNase I sensitivity within the two tissues. Genes that were differentially expressed in seedling and callus were frequently associated with DH sites in both tissues. The DNA sequences contained within the DH sites were hypomethylated, consistent with what is known about active gene regulatory elements. Interestingly, tissue-specific DH sites located in the promoters showed an elevated level of DNA methylation. A distinct elevation of H3K27me3 was associated with intergenic DH sites. These results suggest that epigenetic modifications play a role in the dynamic changes of the numbers and DNase I sensitivity of DH sites during development. To do associated analysis with DNase I hypersensitive sites in rice, we performed ChIP-seq to identify the positions of three histone modifications (H3K4me2, H3K36me3 and H4K12ac) in the rice genome (leaf tissue only - not callus). The ChIP DNA from seedling of each experiment was sequenced on one lane of Illumina Genome Analyzer.

ORGANISM(S): Oryza sativa

SUBMITTER: Yufeng Wu

PROVIDER: E-GEOD-26733 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

High-resolution mapping of open chromatin in the rice genome.

Zhang Wenli W Wu Yufeng Y Schnable James C JC Zeng Zixian Z Freeling Michael M Crawford Gregory E GE Jiang Jiming J

Genome research 20111122 1

Gene expression is controlled by the complex interaction of transcription factors binding to promoters and other regulatory DNA elements. One common characteristic of the genomic regions associated with regulatory proteins is a pronounced sensitivity to DNase I digestion. We generated genome-wide high-resolution maps of DNase I hypersensitive (DH) sites from both seedling and callus tissues of rice (Oryza sativa). Approximately 25% of the DH sites from both tissues were found in putative promote ...[more]

PMID: 22110044

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Project description:Nucleosome positioning dictates the DNA accessibility for regulatory proteins, and thus is critical for gene expression and regulation. It has been well documented that only a subset of nucleosomes are reproducibly positioned (phased) in eukaryotic genomes. The most prominent example of phased nucleosomes is the context of genes, where phased nucleosomes flank the transcriptional starts sites (TSSs). It is unclear, however, what factors influence nucleosome phasing in regions that are not close to genes. We performed a combinational mapping of nucleosome positioning and DNase I hypersensitive sites (DHSs) across the rice genome. We discovered that DHSs located in a variety of contexts, both genic and intergenic, were flanked by strongly phased nucleosome arrays. Our results support the barrier model for nucleosome organization as a general feature of eukaryote genomes, including plant genomes, and not limited to TSSs. Specifically, regions bound with regulatory proteins, including intergenic regions, can serve as barriers that organize phased nucleosome arrays on both sides. Our results also suggest that rice DHSs often span a single, phased nucleosome, similar to the H2A.Z-containing nucleosomes observed in DHSs in the human genome. We propose that genome-wide nucleosome positioning in the eukaryotic genomes is orchestrated by genomic regions associated with regulatory proteins. Rice chromatin was digested by micrococcal nuclease (MNase) into mono-nucleosome size. Mono-nucleosomal DNA was isolated and sequenced (MNase-seq) using Illumina sequencing platforms. We obtained a total of 38 million (M) single-end reads from our first MNase-seq experiment and mapped ~26 M to unique positions in the rice genome. We also conducted pair-end sequencing of an independent MNase-seq library, obtained 274 M paired-end reads, and mapped ~231 M read pairs to unique positions in the rice genome.We applied a strategy of combinational mapping of nucleosome positioning and DHSs (GSE26610) to examine whether nucleosome positioning is associated with all cis-regulatory elements in the rice genome. All datasets used in the analysis were developed using rice leaf tissue in the same developmental stage