Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA156127 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:Missense mutations in the TP53 gene are frequent genetic alterations in human tumor tissue and cell lines. In contrast to wild-type p53, the mutant p53 (mutp53) protein has lost the transcriptional activity towards pro-apoptotic and growth arrest genes, but retained the property to interact with DNA in a structure-specific fashion. Expression of mutp53 is advantageous for tumor cells, however the molecular mechanism of mutp53 action is still not known. We used the glioblastoma-derived U-251 MG human cell line to analyze DNA binding of mutant p53 (R273H mutation) on a Nimblegen custom 135k tiling array and to correlate mutp53 binding regions with the epigenetic state and occupation by other transcription factors (ETS1 and SP1). We found that mutp53-binding regions are G/C-rich and are located around transcriptional start sites (TSS) of many protein-coding genes, which in most cases are active, but are not always regulated upon transient mutp53 depletion. We propose a model which does not only rely on interactions of mutp53 with diverse transcriptional regulators at active promoters, but primarily is based on a DNA binding activity of mutp53. We designed a Nimblegen custom 135k tiling array that covers a large set of putative and known p53 (wild-type and mutant) target genes in the human genome. For analysis of the epigenetic state of genes covered by the tiling array in control and mutant p53-depleted U251 cells we focused on changes in active histone marks, H3K4me3 and H3K9Ac, and RNA polymerase II recruitment and processivity. H3K4me3 and H3K9Ac marks are enriched in active promoter regions and the phosphorylation of serine 5 (S5-P) and serine 2 (S2-P) in the CTD of RNA polymerase II have been described to define initiated and elongating complexes, respectively. We performed the ChIP-chip experiments for H3K4me3, H3K9Ac, RNA polymerase II (S5-P) and RNA polymerase II (S2-P) from U251 cells transfected with p53-specific siRNA or control siRNA (2 biological replicates each). To analyze binding of mutant p53 to the genes covered by the tiling array we performed mutant p53 ChIP-chip experiments in 4 biological replicates of. In addition, we analyzed the distribution of SP1 and ETS1 binding sites in 3 biological replicates.
2012-12-10 | E-GEOD-35453 | biostudies-arrayexpress
Project description:Gene expression analysis of U251 human glioblastoma cell line
| PRJNA156129 | ENA
Project description:STAT1 ChIP-chip performed on Human Hela S3 Cells for three different platforms. Nimblegen ENCODE arrays which comprise 50mer oligonucleotides spaces every 38bps (overlapping by 12nts) (5 biological replicates), custom maskless array tiling most of ENCODE with 50mer oligonucleotides end-to-end (3 biological replicates) and custom maskless array tiling most of ENCODE with 36mer oligonucleotides end-to-end (2 biological replicates). The chromatin-immunoprecipitation protocol is the same for all samples, however the labelling and hybridization protocols differ between Nimblegen and custom maskless arrays. Keywords = Transcription Factor Binding, STAT1, ChIP-chip, Human, Genome Tiling Arrays Keywords: other
2005-05-27 | GSE2714 | GEO
Project description:BCL6 ChIP on chip using a Nimblegen custom tiling array
| PRJNA99725 | ENA
Project description:Using human U251 glioblastoma cells with endogenous mutp53 expression as a model, we performed a ChIP-chip analysis of mutp53 binding sites on a custom tiling array, coupled with global expression profiling and an analysis of the epigenetic status of mutp53 regulated promoters. Mutp53 binds preferentially, and independent of other transcription factors (e.g. ETS1 and SP1), to G/C-rich DNA stretches around transcriptional start sites (TSS) of many genes. Mutp53-bound regions are frequently located in CpG islands and are highly prone to adopt non-B DNA conformation(s). Analysis of the transcriptional status of mutp53-regulated genes demonstrated that mutp53 generally modulates transcription from active promoters marked by H3K4me3. Based on our data we propose a dual mode model of mutp53 GOF, which includes both stochastic and deterministic components. On a local scale, mutp53 acts as a basal transcriptional co-factor that has the potential to bind autonomously and selectively to non-B DNA structures around TSSs of active genes and to modulate transcription rates of many genes in a context and stimulus-dependent fashion. Resulting stochastic alterations generate transcriptional plasticity and enhance transcriptional competence on a global scale. This SuperSeries is composed of the SubSeries listed below.
2012-12-10 | GSE35500 | GEO
Project description:Using human U251 glioblastoma cells with endogenous mutp53 expression as a model, we performed a ChIP-chip analysis of mutp53 binding sites on a custom tiling array, coupled with global expression profiling and an analysis of the epigenetic status of mutp53 regulated promoters. Mutp53 binds preferentially, and independent of other transcription factors (e.g. ETS1 and SP1), to G/C-rich DNA stretches around transcriptional start sites (TSS) of many genes. Mutp53-bound regions are frequently located in CpG islands and are highly prone to adopt non-B DNA conformation(s). Analysis of the transcriptional status of mutp53-regulated genes demonstrated that mutp53 generally modulates transcription from active promoters marked by H3K4me3. Based on our data we propose a dual mode model of mutp53 GOF, which includes both stochastic and deterministic components. On a local scale, mutp53 acts as a basal transcriptional co-factor that has the potential to bind autonomously and selectively to non-B DNA structures around TSSs of active genes and to modulate transcription rates of many genes in a context and stimulus-dependent fashion. Resulting stochastic alterations generate transcriptional plasticity and enhance transcriptional competence on a global scale. This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2012-12-10 | E-GEOD-35500 | biostudies-arrayexpress
Project description:The human TP53 gene is frequently mutated in tumors and cell lines. Unlike other tumor suppressors that are commonly inactivated by deletions or nonsense mutations, the majority of p53-mutations are missense point mutations that result in the expression of a full-length protein with an altered amino acid that has lost sequence specific DNA-binding. Expression of mutant p53 (mutp53) confers advantages to tumor cells and transcriptional regulation of several genes mediating the beneficial effects has been shown to play a role. However, molecular mechanisms of transcriptional regulation by mutp53 are still poorly understood. We used the glioblastoma-derived U-251 MG human cell line endogenously expressing mutp53 protein (R273H mutation) to analyze gene expression profiles on Agilent Whole Human Genome Microarray after transient and stable depletion of mutp53 expression. Gene expression data was correlated with a ChIP study on a custom tiling array to understand the contribution of endogenously expressed mutp53 to transcriptional regulation.
2012-12-10 | GSE35454 | GEO
Project description:ChIP-chip on custom NimbleGen genomic tiling arrays
| PRJNA105111 | ENA
Project description:Glioma stem cells (GSCs) have been identified in glioma tissues and suggested to play important roles in the tumorigenesis of glioblastoma multiform (GBM). We established a novel cellular bioinformative pipeline that consisted of principal component analysis (PCA) with factor loading, intracellular pathway analysis, and immunopathway analysis and attempted to clarify the differences in gene expression profiles comprehensively among GSCs, a glioma cell line (U251), and a human GBM tissue (hGBM). To this end, we extracted total RNAs from the GSCs, U251, and the hGBM, performed microarray, and applied the data to the bioinformatics analyses described above. As the results, PCA clearly distinguished the three groups. Moreover, the second principal component (PC2) distinguished the GSCs from the hGBM and U251; it reflected the characteristics of stemness. The factor loading for PC2 suggested MYCN, DPP4, and, MIF as contributing factors to the stemness of GSCs. We clarify the similarities and differences among samples such as the GSCs, U251, and hGBM.
2019-07-01 | GSE124145 | GEO