Stranded RNA-seq were performed on total RNA following ribosomal RNAs depletion (Ribo-zero removal kit, illumina) for 3 brain , 8 IDHwt and 5 IDHmut glioma samples.
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PROVIDER: PRJNA510124 | ENA |
REPOSITORIES: ENA
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Project description:Stranded RNA-seq were performed on total RNA following ribosomal RNAs depletion (Ribo-zero removal kit, illumina) for glioblastoma stem cell
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Project description:In human, the 39 coding HOX genes and 18 referenced non-coding antisense transcripts are arranged in four genomic clusters named HOXA, B, C, and D. This highly conserved family belongs to the homeobox class of genes that encode transcription factors required for normal development. Therefore, HOX gene deregulation might contribute to the development of many cancer types. Here, we study HOX gene deregulation in adult glioma, a common type of primary brain tumor. We performed extensive molecular analysis of tumor samples, classified according to their isocitrate dehydrogenase (IDH1) gene mutation status, and of glioma stem cells. We found widespread expression of sense and antisense HOX transcripts only in aggressive (IDHwt) glioma samples, although the four HOX clusters displayed DNA hypermethylation. Integrative analysis of expression-, DNA methylation- and histone modification signatures along the clusters revealed that HOX gene upregulation relies on canonical and alternative bivalent CpG island promoters that escape hypermethylation. H3K27me3 loss at these promoters emerges as the main cause of widespread HOX gene upregulation in IDHwt glioma cell lines and tumors. Our study provides the first comprehensive description of the epigenetic changes at HOX clusters and their contribution to the transcriptional changes observed in adult glioma. It also identified putative "master" HOX proteins that might contribute to the tumorigenic potential of glioma stem cells.
2021-03-09 | GSE161438 | GEO
Project description:Aberrant DNA methylation is a well-defined feature of cancer cells that is commonly associated to transcriptional alteration. Nonetheless, a primary role of this defect in genome-wide cancer-associated gene misregulation is still being questioned. Here, we used adult glioma, a widespread type of brain tumor, to evaluate the relative contribution of DNA methylation-dependent and -independent mechanisms on transcriptional alteration at CpG-island/promoter-associated genes in cancer cells. By extensive molecular analyses conducted in both IDH wild-type (IDHwt) and IDH mutated (IDHmut) samples, we show that DNA hypermethylation affects only a minority of genes that show a loss or a gain of expression. In IDHwt samples, for instance, more than 75% of aberrantly repressed genes do not display DNA methylation defect at their CpG-island promoter. Rather, an alteration in the H3K27me3 signature is the predominant molecular defect at misregulated genes. We also observed that a bivalent chromatin signature in stem cell might not only predispose genes to hypermethylation, as widely documented, but more generally to all type of transcriptional alterations. In addition, we evidenced that transcriptional strength in healthy brain influences the choice between DNA methylation- or H3K27me3- associated silencing pathway at repressed genes in glioma. Combined our study supports a model whereby the altered developmental control of H3K27me3 dynamics, and more specifically defects in the interplay between polycomb protein complexes and brain-specific transcriptional machinery, is the main cause of transcriptional alteration in glioma cells. Together our study provides a comprehensive and revisited picture of epigenetic gene deregulations in cancer. Our observations are also of importance for the design of drugs that aims to target cancer epigenetic defects.
2019-09-09 | GSE123892 | GEO
Project description:We describe Ribo Mega-SEC, a powerful approach for the separation and biochemical analysis of mammalian polysomes and ribosomal subunits using Size Exclusion Chromatography and uHPLC, which was achieved within 15 min from sample injection to fraction collection. Ribo Mega-SEC reproducibly shows translating ribosomes exist predominantly in polysome complexes in extracts isolated from human cell lines and mouse liver tissue, which alter in response to starvation. Ribo Mega-SEC provides a rapid, efficient, convenient and highly reproducible method for studying functional translation complexes and is easily combined with high-through put analysis such as proteomics and RNA-Seq, or with structural analysis using electron microscopy. We propose that Ribo Mega-SEC analysis is an accessible alternative to traditional polysome profiling using sucrose density gradients.
2018-08-10 | PXD008913 | Pride
Project description:mRNAs are generally assumed to be loaded instantly with ribosomes upon entry into the cytoplasm. To measure ribosome density on nascent mRNA, we developed nascent Ribo-Seq (nRibo-Seq) by combining Ribo-Seq with progressive 4-thiouridine labelling. In mouse macrophages, we experimentally determined, for the first time, the lag between the appearance of nascent RNA and its association with ribosomes, which was calculated to be 20 - 22 min for bulk mRNA, and approximated the time it takes for mRNAs to be fully loaded with ribosomes to be 41 - 44 min. Notably, ribosomal loading time is adapted to gene function as rapid loading was observed with highly regulated genes. The lag and ribosomal loading time correlate positively with ORF size and mRNA half-life, and negatively with tRNA adaptation index. Similar results were obtained in mouse embryonic stem cells, where the lag in ribosome loading was even more pronounced with 35 - 38 min. We validated our measurements after stimulation of macrophages with lipopolysaccharide, where the lag between cytoplasmic and translated mRNA leads to uncoupling between input and ribosome-protected fragments. Uncoupling is stronger for mRNAs with long ORFs or half-lives, a finding we also confirmed at the level of protein production by nascent chain proteomics. As a consequence of the lag in ribosome loading, ribosome density measurements are distorted when performed under conditions where mRNA levels are far from steady state expression, and transcriptional changes affect ribosome density in a passive way. This study uncovers an unexpected and considerable lag in ribosome loading, and provides guidelines for the interpretation of Ribo-Seq data taking passive effects on ribosome density into account.
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Project description:mTRAN proteins are are plant specific-components of the mitoribosome. To asses of loss-of-function mtran1 mtran2 double mutants show decreased translation rates, we performed ribosome footprinting coupled to RNA-seq (Ribo-seq).
2023-09-01 | E-MTAB-13059 | biostudies-arrayexpress
Project description:Ribo-seq was performed on cells treated with Tetracycline and Tylosin to to investigate the effect on ribosome pausing across the transcriptome of Escherichia coli MG1655.
2022-10-15 | E-MTAB-12242 | biostudies-arrayexpress
Project description:Single Centre, open label assignment phase II clinical study.
To evaluate the effect of oral 200mg Methylene Blue tablets (administered 8x25mg) prior to endoscopy on double stranded DNA breaks in colonic biopsy samples assessed by histone gamma H2AX analysis, compared to control biopsies.
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Project description:Charcot-Marie-Tooth (CMT) disease can be caused by mutations in Aminoacyl-tRNA-Synthetases, including G240R mutation in Glycyl-tRNA-Synthetase (GARS). Ribo-seq generates snapshots of translating ribosomes on mRNA and therefore allows analysis of ribosome pausing mRNA. Here we performed Ribo-seq on lysates of HEK293T cells overexpressing GARS, WT or G240R, to dissect mechanism of CMT linked with translation. We found that GARS G240R causes pausing of ribosomes with glycine codons in A-site. The effect is specific for 21 nt ribosome-protected fragments, produced by ribosomes with empty A-sites, suggestive of the deficit of charged Glycyl-tRNA in GARS G240R-CMT.
2021-09-14 | E-MTAB-10342 | biostudies-arrayexpress
Project description:Ribosomal DNA (rDNA) arrays are highly repetitive regions of the genome which encode essential genes required to produce ribosomes. DNA double-stranded breaks (DSBs) generated within rDNA genes elicit a unique cellular response involving robust transcriptional silencing and nucleolar reorganization into ‘cap’ structures at the nucleolar periphery. This process is coordinated by the nucleolar scaffolding protein TCOF1, which functions to recruit the DNA repair proteins NBS1 and TOPBP1 that activate the ATM and ATR kinases, resulting in ribosomal RNA (rRNA) transcriptional silencing and nucleolar segregation. However, the DNA damage and repair response at rDNA arrays remains incompletely understood. Here, we investigate the cellular response to rDNA DSBs using proteomics and genetic CRISPR-Cas9 screening. We show that the protein UFMylation pathway and the HUSH complex are important for cell viability and survival in response to rDNA DSBs, and that the E3 UFM1-ligase UFL1 and its heterodimer DDRGK1 are associated with TCOF1 at nucleolar caps. Loss of UFL1 leads to impaired ATM activation, reduced rRNA transcriptional silencing, and an overall reduction in nucleolar segregation. We identified ATM, UNC45A and SMC6 as UFMylated proteins, in which UFMylation may facilitate ATM activation and segregation of damaged rDNA to the nucleolar periphery. Altogether, our findings provide the first evidence for a role for UFMylation in rDNA DSB repair.
2024-09-16 | PXD048568 | Pride