Splicing towards noncoding isoforms in colorectal carcinoma is associated with tumor hypoxia and the DNA damage response
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE81513 | GEO | 2016/07/28
SECONDARY ACCESSION(S): PRJNA321835
REPOSITORIES: GEO
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Project description:Tumor hypoxia is associated with poor patient outcome and resistance to therapy. It is associated with a rapid decline in protein production mediated through mTOR signalling. Here we show that it also leads to widespread changes in splicing and a global shift towards the expression of noncoding isoforms, thus providing a novel and orthogonal mechanism by which cells can modulate protein expression. Examination of mRNA levels in HCT116 cells after 0 hr, 1 hr, 2 hr and 24 hr in hypoxia. Three biological replicates each.
2016-07-28 | E-GEOD-81513 | biostudies-arrayexpress
Project description:Tumour hypoxia is associated with poor patient outcome and resistance to therapy. It is accompanied by widespread changes in gene expression mediated largely through the transcription factors HIF1/2/3α. Hypoxia impacts on multiple pathways throughout the cell and has widespread effects on phenotype. Here we use sample-specific annotation approaches to determine the changes in transcript architecture that arise as result of alternative splicing in hypoxic cells. Using in vivo data generated from a time course in reduced oxygenation we identified genome-wide switching between coding and noncoding isoforms, including a significant number of components of the DNA damage response pathway. Notably, HDAC6, a master regulator of the cytotoxic response, and TP53BP1, which sits at the nexus of the double-strand break repair pathway, both underwent a marked transition towards an intron-retention pattern with a concomitant decline in protein levels. These transitions from coding to noncoding isoforms were recapitulated in a large and independent cohort of 499 colorectal samples taken from The Cancer Genome Atlas (TCGA). The set of altered genes was enriched for multiple components of the Fanconi Anaemia, nucleotide excision and double-strand break repair pathways, and together correlating with tumour status at last contact. Altogether, these data demonstrate a new role for hypoxia-driven alternative splicing in regulating DNA damage response, and highlight the importance of considering alternative splicing as a critical factor in our understanding of human disease.
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Project description:Purpose: mRNA translation into protein is highly regulated, but the role of mRNA isoforms, noncoding RNAs (ncRNAs), and genetic variants has yet to be systematically studied. Using high-throughput sequencing (RNA-seq), we have measured cellular levels of mRNAs and ncRNAs, and their isoforms, in lymphoblast cell lines (LCL) and in polysomal fractions, the latter shown to yield strong correlations of mRNAs with expressed protein levels. Analysis of allelic RNA ratios at heterozygous SNPs served to reveal genetic factors in ribosomal loading. Methods: RNA-seq was performed on cytosolic extracts and polysomal fractions (3 ribosomes or more) from three lymphoblastoid cell lines. As each RNA fraction was amplified (NuGen kit), and relative contributions from various RNA classes differed between cytosol and polysomes, the fraction of any given RNA species loaded onto polysomes was difficult to quantitate. Therefore, we focused on relative recovery of the various RNA classes and rank order of single RNAs compared to total RNA. Results: RNA-seq of coding and non-coding RNAs (including microRNAs) in three LCLs revealed significant differences in polysomal loading of individual RNAs and isoforms, and between RNA classes. Moreover, correlated distribution between protein-coding and non-coding RNAs suggests possible interactions between them. Allele-selective RNA recruitment revealed strong genetic influence on polysomal loading for multiple RNAs. Allelic effects can be attributed to generation of different RNA isoforms before polysomal loading or to differential loading onto polysomes, the latter defining a direct genetic effect on translation. Several variants and genes identified by this approach are also associated with RNA expression and clinical phenotypes in various databases. Conclusions: These results provide a novel approach using complete transcriptome RNA-seq to study polysomal RNA recruitment and regulatory variants affecting protein translation. cells from 3 samples were grown to 5x105 cells/mL density in T75 tissue culture flask and harvested, total RNA and polysome bound RNA was sequenced by Ion Proton
2015-06-30 | E-GEOD-66135 | biostudies-arrayexpress
Project description:Purpose: mRNA translation into protein is highly regulated, but the role of mRNA isoforms, noncoding RNAs (ncRNAs), and genetic variants has yet to be systematically studied. Using high-throughput sequencing (RNA-seq), we have measured cellular levels of mRNAs and ncRNAs, and their isoforms, in lymphoblast cell lines (LCL) and in polysomal fractions, the latter shown to yield strong correlations of mRNAs with expressed protein levels. Analysis of allelic RNA ratios at heterozygous SNPs served to reveal genetic factors in ribosomal loading. Methods: RNA-seq was performed on cytosolic extracts and polysomal fractions (3 ribosomes or more) from three lymphoblastoid cell lines. As each RNA fraction was amplified (NuGen kit), and relative contributions from various RNA classes differed between cytosol and polysomes, the fraction of any given RNA species loaded onto polysomes was difficult to quantitate. Therefore, we focused on relative recovery of the various RNA classes and rank order of single RNAs compared to total RNA. Results: RNA-seq of coding and non-coding RNAs (including microRNAs) in three LCLs revealed significant differences in polysomal loading of individual RNAs and isoforms, and between RNA classes. Moreover, correlated distribution between protein-coding and non-coding RNAs suggests possible interactions between them. Allele-selective RNA recruitment revealed strong genetic influence on polysomal loading for multiple RNAs. Allelic effects can be attributed to generation of different RNA isoforms before polysomal loading or to differential loading onto polysomes, the latter defining a direct genetic effect on translation. Several variants and genes identified by this approach are also associated with RNA expression and clinical phenotypes in various databases. Conclusions: These results provide a novel approach using complete transcriptome RNA-seq to study polysomal RNA recruitment and regulatory variants affecting protein translation.
2015-06-30 | GSE66135 | GEO
Project description:We examined the transcriptional changes modulated by knocking out ERβ and reintroduction of ERβ1 and ERβ5 isoforms by perfroming global transcriptome analysis. ERβ was knocked out in U87 cells using CRISPR/Cas9 system and reintroduced the ERβ1 and ERβ5 isoforms in knockout background. RNA was isolated from control U87, U87-ERβ-KO, U87-ERβ1 and U87-ERβ5 cells and utilized for RNA-seq analysis. Our results demonstrated that ERβ-KO, ERβ1 and ERβ5 modulated unique pathways including NF-κB singaling, Jak/STAT pathway and mTOR signaling.
2018-04-10 | GSE104296 | GEO
Project description:Long-read nanopore sequencing is capable of continuously reading thousands of base pairs. Here, we report the application of nanopore sequencing technology for analysing hypoxia-specific transcriptomes in normal liver and liver cancer cell lines, which help us to better understand the mechanism of cell survival and metastasis under hypoxia. We conducted transcriptomic sequencing of normal liver and liver cancer cell lines under normoxia or hypoxia, founding that long-read sequencing could detect thousands of hypoxia-specific isoforms and unannotated novel genes. At the cellular level, we have verified that the novel gene 644 is most up-regulated novel gene under hypoxic conditions. We observed that the novel gene 644 possesses classical mRNA characteristics, with its CDS region encoding 91 amino acids. Through protein structure predictions, we discovered that the novel gene 644 contains a transmembrane domain. Experimental validation confirmed that the novel gene 644 is a membrane protein, and knockdown of the novel gene 644 significantly suppresses the proliferative capacity of liver cancer cells under hypoxic conditions. Furthermore, we revealed the protein structure alteration of hypoxia specific isoforms with molecular dynamics simulation. The results indicate that our hypoxic dataset can serve as a foundation for the structural simulation of hypoxic-specific proteins. In summary, we have presented a hypoxic-specific third-generation sequencing dataset for further analysis, which provides sufficient details on cellular transcriptomes and is particularly valuable for understanding the survival and metastasis of tumor under hypoxic conditions. From this dataset, we have validated the importance of novel gene 644 for tumor survival under hypoxia and identified alterations in hypoxic-specific protein structures. These discoveries can bring us new knowledge about hypoxia, leading to the identification of potential tumor treatment targets and biomarkers.
2024-05-28 | GSE263126 | GEO
Project description:The aim of this study was to obtain a landscape of alternative splicing (AS) in human hepatocellular carcinoma (HCC). We applied hybrid sequencing by integrating Pacbio long-read and Illumina short-read RNA sequencing data from 8 patient-derived HCC cell lines, and used an immortalized hepatocyte cell line as reference. This study revealed features of annotated and novel splice variants in HCC cells, including transcript length, AS type and protein changes. We also identified novel isoforms and tumor specific isoforms, which may represent potential biomarkers and targets for therapeutic development.
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Project description:Eukaryotic genes generate multiple mRNA transcript isoforms though alternative transcription, splicing, and polyadenylation. However, the relationship between human transcript diversity and protein production is complex as each isoform can be translated differently. We fractionated a polysome profile and reconstructed transcript isoforms from each fraction, which we term Transcript Isoforms in Polysomes sequencing (TrIP-seq). Analysis of these data revealed regulatory features that control ribosome occupancy and translational output of each transcript isoform. We extracted a panel of 5′ and 3′ untranslated regions that control protein production from an unrelated gene in cells over a 100-fold range. Select 5′ untranslated regions exert robust translational control between cell lines, while 3′ untranslated regions can confer cell-type-specific expression. These results expose the large dynamic range of transcript-isoform-specific translational control, identify isoform-specific sequences that control protein output in human cells, and demonstrate that transcript isoform diversity must be considered when relating RNA and protein levels.
2016-01-11 | GSE69352 | GEO
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