The DNA methylation landscape of human melanoma
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Xiwei Wu
PROVIDER: E-GEOD-71748 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Similar Datasets
Project description:Melanoma genomes are often characterized by large numbers of sunlight-induced mutations. However, epigenetic alterations, in the form of aberrant DNA methylation patterns, are also abundant. Using MIRA-seq, we have carried out a comprehensive characterization of the DNA methylome in a series of metastatic melanoma samples and catalogued the methylation changes relative to normal melanocytes, the presumed cells of origin for these tumors. Individual melanoma tumors contained up to several thousand hypermethylated regions. We discovered 179 tumor-specific methylation peaks that were present in all (27/27) melanomas and may lend themselves as effective disease biomarkers, and 3124 methylation peaks were present in >40% of the tumors. We specifically examined the relationship between presence of the Polycomb mark, H3K27me3 in melanocytes and tumor-specific DNA methylation in melanoma. We found that 150 of the approximately 1,200 tumor-associated methylation peaks near transcription start sites (TSS) were H3K27me3-marked in melanocytes. Notably, DNA methylation in melanoma was specific for distinct H3K27me3 peaks rather than for H3K27me3-enriched regions with broad genomic coverage. Yet, there were also numerous H3K27me3 peak-associated TSS regions that were completely resistant to DNA methylation in tumors. Furthermore, a rather large group of genes became methylated in melanoma but lacked H3K27me3 in melanocytes. There was no relationship between presence of BRAF V600 mutations and the number of methylation peaks in individual tumors. Gene expression analysis showed a strong signature of upregulated immune response genes in melanomas presumably as a result of lymphocyte infiltration. Genes down-regulated in tumors were enriched for melanocyte differentiation and pigmentation factors. Overall, there was limited correlation between tumor-associated DNA methylation changes and changes in gene expression although distinct melanocyte differentiation genes including KIT, PAX3 and SOX10 became methylated and downregulated in melanoma. Examination of H3K27me3 histone modification in human normal melanocytes.
2016-03-31 | E-GEOD-71692 | biostudies-arrayexpress
Project description:Identification and characterization of HP1BP3 (a human histone H1 homologue) as a novel chromatin retention factor essential for the co-transcriptional processing of pri-miRNA. We generated BAC transgenic cells at 80% confluency (~1x107) were cross-linked with 1% formaldehyde for 10 minutes at 37°C, and quenched with 125 mM glycine at room temperature for 5 minutes. The fixed cells were washed twice with cold PBS, scraped, and transferred into 1 ml PBS containing protease inhibitors (Roche). After centrifugation at 700 g for 4 minutes at 4°C, the cell pellets were resuspended in 100 μl ChIP lysis buffer (1% SDS, 10 mM EDTA, 50 mM Tris-HCl [pH 8.1] with protease inhibitors) and sonicated at 4°C with a Bioruptor (Diagenode) (30 seconds ON and 30 seconds OFF at highest power for 15 minutes). The sheared chromatin with a fragment length of ~200 â 600 bp) was centrifuged at 20,000 g for 15 minutes at 4°C). 100 μl of the supernatant was used for ChIP or as input. A 1:10 dilution of the solubilized chromatin in ChIP dilution buffer (0.01% SDS, 1.1% Triton X-100, 1.2 mM EDTA, 167 mM NaCl 16.7 mM Tris-HCl [pH 8.1]) was incubated at 4°C overnight with 6 μg/ml of a goat anti-GFP (raised against His-tagged full-length eGFP and affinity-purified with GST-tagged full-length eGFP). Immunoprecipitation was carried out by incubating with 40 μl pre-cleared Protein G Sepharose beads (Amersham Bioscience) for 1 hour at 4°C, followed by five washes for 10 minutes with 1ml of the following buffers: Buffer I: 0.1% SDS, 1% Triton X-100, 2 mM EDTA, 20 mM Tris-HCl [pH 8.1], 150 mM NaCl; Buffer II: 0.1% SDS, 1% Triton X-100, 2 mM EDTA, 20 mM Tris-HCl [pH 8.1], 500 mM NaCl; Buffer III: 0.25 M LiCl, 1% NP-40, 1% deoxycholate, 1 mM EDTA, 10 mM Tris-HCl [pH 8.1]; twice with TE buffer [pH 8.0]. Elution from the beads was performed twice with 100 μl ChIP elution buffer (1% SDS, 0.1 M NaHCO3) at room temperature (RT) for 15 minutes. Protein-DNA complexes were de-crosslinked by heating at 65°C in 192 mM NaCl for 16 hours. DNA fragments were purified using QiaQuick PCR Purification kit (QIAGEN) and eluted into 30 μl H2O according to the manufacturerâs protocol after treatment with RNase A and Proteinase K.
2016-07-24 | E-GEOD-77854 | biostudies-arrayexpress
Project description:Estrogen-based treatments have numerous extra-reproductive effects. On the one hand, they have protective metabolic actions against abdominal fat accumulation, type 2 diabetes, liver steatosis,⦠But, on the other hand, the oral route of administration, presumably due to a hepatic impact on liver-derived coagulation factors, appears to increase risks of venous thrombosis and pulmonary embolism. The characterization of liver genes expression regulations by these hormones thereby appears of utmost interest, but the estrogen-sensitive transcriptome of liver and ER cistrome was so far explored under chronic hormonal treatment. To explore the early steps of these mechanisms, we determined here the short-term changes in liver transcriptional responses to acute E2 administration, and aimed to characterize the mechanisms allowing these programs to be engaged. Collectively, through the comparison of mice expressing or not ER, our data demonstrate that acute administration of E2 provokes genes expression variations which fit with a crucial role of ER in the prevention of liver steatosis in mice fed with a high fat diet by E2. They also evidenced higher proportion of ER binding sites (BSs) located at the direct vicinity (distance <3kb) of regulated genes than what is determined in human cancer cell models. Besides this specific aspect of ER cistrome in vivo, we unexpectedly found that 40 % of the BSs of the pioneer factor Foxa2 were dependent upon the expression of ER that indirectly influences the distribution of the nucleosomes harbouring a dimethylated H3K4 around these Foxa2 sites. Whole-genome analysis of estrogen receptor (ER) and FOXA2 binding events associated with the cartography of two histone marks (H3K4me2 and H3K27ac) in livers from wild-type or ERKO mice.
2016-05-13 | E-GEOD-70346 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2016-07-24 | E-GEOD-77856 | biostudies-arrayexpress
Project description:Reward-related memory is an important factor in cocaine seeking. One necessary signaling mechanism for long-term memory formation is the activation of poly(ADP-ribose) polymerase-1 (PARP-1), via poly(ADP-ribosyl)ation. We demonstrate herein that auto-poly(ADP-ribosyl)ation of activated PARP-1 was significantly pronounced during retrieval of cocaine-associated contextual memory, in the central amygdala (CeA) of rats expressing cocaine-conditioned place preference (CPP). Intra-CeA pharmacological and shRNA depletion of PARP-1 activity during cocaine-associated memory retrieval abolished CPP. In contrast, PARP-1 inhibition after memory retrieval did not affect CPP reconsolidation process and subsequent retrievals. Chromatin Immuoprecipitation (ChIP) sequencing revealed that PARP-1 binding in the CeA is highly enriched in genes involved in neuronal signaling. We identified amongst PARP targets in CeA a single gene, yet uncharacterized and encoding a putative transposase inhibitor, at which PARP-1 enrichment dramatically increases during cocaine-associated memory retrieval and positively correlates with CPP. Our findings have important implications for understanding drug-related behaviors, and suggest possible future therapeutic targets for drug abuse. 4 samples, each is pooled central amygdalae tissues collected from 2 rats. Rats were trained for cocaine-conditioned place-preference (CPP), tissues were harvested immediately following cocaine-CPP retrieval. Three groups of rats were used: high cocaine CPP, low cocaine CPP and control saline only trained rats.
2016-06-25 | E-GEOD-83718 | biostudies-arrayexpress
Project description:Bacterial toxin-antitoxin systems (TASs) are thought to respond to various stresses, often inducing growth-arrested (persistent) sub-populations of cells whose housekeeping functions are inhibited. However, it is not always clear whether specific targets of orthologous RNAse toxins are responsible for their phenotypic effect, which has made it difficult to accurately place the multitude of TASs within cellular and adaptive regulatory networks. Here we show that the TAS HigBA can promote and inhibit bacterial growth dependent on the dosage of HigB, a toxin regulated by the DNA damage (SOS) repressor LexA in addition to its antitoxin HigA, and the target selectivity of HigBâs mRNA cleavage activity. HigB reduced the expression of an efflux pump that is toxic to a polarity control mutant, cripples the growth of cells lacking LexA and targets the cell cycle circuitry. Thus, TASs can have outcome switching activity in bacterial adaptive (stress) and systemic (cell cycle) networks. DNA binding of the antitoxin HigA and the SOS regulator LexA was analysed by chromatin immunoprecipitation-deep sequencing, and found to overlap at only one locus, the HigBA TA system promoter
2016-02-17 | E-GEOD-76721 | biostudies-arrayexpress
Project description:Under current models for signal-dependent transcription in eukaryotes, DNA-binding activator proteins regulate the recruitment of RNA polymerase II (Pol II) to a set of target promoters. Yet, recent studies, as well as our results herein, show that Pol II is widely distributed (i.e., "preloaded") at the promoters of many genes prior to specific signaling events. How Pol II recruitment and Pol II preloading fit within a unified model of gene regulation is unclear. In addition, the mechanisms through which cellular signals activate preloaded Pol II across mammalian genomes remain largely unknown. Here we show that the predominant genomic outcome of estrogen signaling is the post-recruitment regulation of Pol II activity through phosphorylation, rather than recruitment of Pol II. Furthermore, we show that negative elongation factor (NELF) binds to estrogen target promoters in conjunction with preloaded Pol II and represses gene expression until the appropriate signal is received. Finally, our studies reveal that the estrogen-dependent activation of preloaded Pol II facilitates rapid transcriptional and post-transcriptional responses which play important physiological roles in regulating estrogen signaling itself. Our results reveal a broad use of post-recruitment Pol II regulation by the estrogen signaling pathway, a mode of regulation that is likely to apply to a wide variety of signal-regulated pathways. ChIP-chip analysis for RNA Pol II, Ser5 phosphorylated RNA Pol II and NELF-A in MCF7 breast cancer cells.
2010-05-14 | E-GEOD-13051 | biostudies-arrayexpress
Project description:This experiment is performed to reveal the novel binding sites of Snai1 transcription factor globally in triple negative breast cancer cell line Hs578T. We also reveal the effect of TGF cytokine on the binding sites of Snai1.
2018-04-25 | E-MTAB-5242 | biostudies-arrayexpress
Project description:This experiment is performed to reveal the novel binding sites of ZEB1 transcription factor globally in triple negative breast cancer cell line Hs578T. We also reveal the effect of TGF cytokine on the binding sites of ZEB1.
2018-04-25 | E-MTAB-5241 | biostudies-arrayexpress
Project description:MacroH2A1 ChIP-chip was performed on custom Nimblegen genomic tiling arrays, to understand the genomic binding patterns of this histone variant and its relationship to gene expression Keywords: ChIP-chip Two macroH2A biological replicates are included. An H3 ChIP-chip sample is included as a control
2010-10-08 | E-GEOD-9607 | biostudies-arrayexpress