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Estrogen induces global reorganization of chromatin structure in human breast cancer cells

ABSTRACT: In the cell nucleus, each chromosome is confined to a chromosome territory. This spatial organization of chromosomes plays a crucial role in gene regulation and genome stability. Recently an additional level of organization has been discovered at the chromosome scale: the spatial segregation into open and closed chromatin to form two genome-wide compartments. Although considerable progress has been made in our knowledge of chromatin organization, a fundamental issue remains the understanding of its dynamic, especially in cancer. To address this issue, we performed genome-wide mapping of intra- and interchromosomal interactions (Hi-C) over the time after estrogen (E2) stimulation of breast cancer cells. To biologically interpret these interactions, we integrated with estrogen receptor alpha (ER alpha) binding events, gene expression and multiple epigenetic marks. We show that E2 induces a global reorganization of genome. More specifically, gene-rich chromosomes as well as areas of open and highly transcribed chromatins are moved spatially closer, thus enabling genes to share transcriptional machinery and regulatory elements. At a lower scale, differentially interacting loci are enriched for cancer proliferation and E2 related genes. We also observe that these differentially interacting loci are correlated with higher ER alpha binding events and gene expression.

ORGANISM(S): Homo sapiens

PROVIDER: GSE51687 | GEO | 2013/10/25

SECONDARY ACCESSION(S): PRJNA224561

REPOSITORIES: GEO

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Project description:In the cell nucleus, each chromosome is confined to a chromosome territory. This spatial organization of chromosomes plays a crucial role in gene regulation and genome stability. Recently an additional level of organization has been discovered at the chromosome scale: the spatial segregation into open and closed chromatin to form two genome-wide compartments. Although considerable progress has been made in our knowledge of chromatin organization, a fundamental issue remains the understanding of its dynamic, especially in cancer. To address this issue, we performed genome-wide mapping of intra- and interchromosomal interactions (Hi-C) over the time after estrogen (E2) stimulation of breast cancer cells. To biologically interpret these interactions, we integrated with estrogen receptor alpha (ER alpha) binding events, gene expression and multiple epigenetic marks. We show that E2 induces a global reorganization of genome. More specifically, gene-rich chromosomes as well as areas of open and highly transcribed chromatins are moved spatially closer, thus enabling genes to share transcriptional machinery and regulatory elements. At a lower scale, differentially interacting loci are enriched for cancer proliferation and E2 related genes. We also observe that these differentially interacting loci are correlated with higher ER alpha binding events and gene expression. 5 time points: before E2 (0h) and after E2 (0.5h, 1h, 4h and 24h). For each time point, there are two lanes per sample and two biological replicate samples. Please note that a processed data file corresponds to the merging of 2 replicates, and that there are 2 lanes per replicates (4 files in total per processed data file). Information about data merging is provided in the title of the sample. For instance : 0h_replicate_1_lane 1 0h_replicate_1_lane 2 0h_replicate_2_lane_1 0h_replicate_2_lane_2 are merged to generate the processed data hic_0h-all-1M.IC.csv.gz. Several bin sizes are provided for the same processed data: hic_0h-all-1M.IC.csv.gz hic_0h-all-2M.IC.csv.gz hic_0h-all-4M.IC.csv.gz hic_0h-all-500k.IC.csv.gz are the same processed data, but with different bin sizes.

Project description:Estrogen receptorï? beta (ER beta) has potent anti-proliferative and anti-inflammatory properties, suggesting that ER beta-selective agonists might be a new class of therapeutic and chemopreventative agents. To understand how ER beta regulates genes, we identified genes regulated by the unliganded and liganded forms of ER alpha and ER beta in U2OS cells. Microarray data demonstrated that virtually no gene regulation occurred with unliganded ER alpha, whereas many genes were regulated by estradiol (E2). These results demonstrate ER alpha requires a ligand to regulate a single class of genes. In contrast, ER beta regulated three classes of genes. Class I genes were regulated primarily by unliganded ER beta. Class II genes were regulated only with E2, whereas Class III genes were regulated by both unliganded ER beta and E2. There were 453 Class I genes, 258 Class II genes and 83 Class III genes. To explore the mechanism whereby ER beta regulates different classes of genes ChIP-seq was performed to identify ER beta binding sites and adjacent transcription factor motifs in regulated genes. AP1 binding sites were more enriched in Class I genes, whereas ERE, NFKB1 and SP1 sites were more enriched in class II genes. ER beta bound to all three classes of genes demonstrating that ER beta binding is not responsible for differential regulation of genes by unliganded and liganded ER beta. The coactivator, NCOA2 was differentially recruited to several target genes. Our findings indicate that the unliganded and liganded forms of ER beta regulate three classes of genes by interacting with different transcription factors and coactivators. U2OS cell lines are stably transfected with a doxycycline-inducible ER alpha or beta. 18 samples are analyzed with triplicate for each of the 6 conditions. The 6 conditions include ER alpha transfected without doxycycline added, ER alpha transfected with doxycycline added, ER alpha transfected with doxycycline added and E2 treatment, ER beta transfected without doxycycline added, ER beta transfected with doxycycline added, and ER beta transfected with doxycycline added and E2 treatment.

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Estrogen induces global reorganization of chromatin structure in human breast cancer cells

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