Alternative expression analysis by RNA sequencing (comparison of 5-FU sensitive and resistant colorectal cancer cell lines)
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE23776 | GEO | 2010/08/25
SECONDARY ACCESSION(S): PRJNA130627
REPOSITORIES: GEO
Similar Datasets
Project description:Changes in alternative splicing are associated with several pathological conditions, including cancer. Microarrays strategies, which allow for the characterization of thousands of alternative splice forms in a single test, can be applied to identify differential alternative splicing events. In this study, a novel splice array platform was developed, including the design of a high-density oligonucleotide array, a labeling procedure, and an algorithm to identify splice events. The array consists of exon probes and thermodynamically balanced junction probes. Suboptimal probes are tagged and considered in the final analysis. An unbiased labeling protocol was developed using random primers. The algorithm used to distinguish changes in expression from changes in splicing was calibrated using internal non-spliced control sequences. The performance of this splice array was first validated with artificial constructs for CDC6, VEGF, and PCBP4 isoforms. The platform was then applied to the analysis of differential splice forms for 8000 genes in lung cancer samples compared to matched normal lung tissue. The expression of lung cancer-associated splice isoforms was validated by RT-PCR. Overexpression of splice isoforms was identified for genes encoding CEACAM1, FHL-1, MLPH, and SUSD2. None of these splicing isoforms had been previously associated with lung cancer. In conclusion, this highly accurate methodology enables the detection of alternative splicing events in complex biological samples, providing a powerful tool to identify novel diagnostic and prognostic biomarkers for cancer and other pathologies. 20 normal/tumor paired specimens. Tumor samples are from non-small cell lung cancer (NSCLC) whereas normals are from adjacent normal lung tissue.
2010-06-21 | E-GEOD-18346 | biostudies-arrayexpress
Project description:Thousands of human genes contain introns ending in NAGNAG motifs (N any nucleotide), where both NAGs can function as 3' splice sites, yielding isoforms differing by inclusion/exclusion of just three bases. However, the functional importance of NAGNAG alternative splicing is highly controversial. Using very deep RNA-Seq data from sixteen human and eight mouse tissues, we found that approximately half of alternatively spliced NAGNAGs undergo tissue-specific regulation and that regulated events have been selectively retained: alternative splicing of strongly tissue-specific NAGNAGs was ten times as likely to be conserved between species as for non-tissue-specific events. Further, alternative splicing of human NAGNAGs was associated with an order of magnitude increase in the frequency of exon length changes at orthologous mouse/rat exon boundaries, suggesting that NAGNAGs accelerate exon evolution. Together, our analyses show that NAGNAG alternative splicing constitutes a major generator of tissue-specific proteome diversity and accelerates evolution of proteins at exon-exon boundaries.
2012-01-05 | GSE30017 | GEO
Project description:Although splicing occurs in most multi-exon genes, the generation of distinct isoforms through the alternate use of mutually exclusive exons is less prevalent. As exon-switching events have the potential to give rise to isoforms with different cellular functions, we have explored the role of the muscle-specific (Mef2Da2) and ubiquitously expressed (Mef2Da1) isoforms of the transcription factor Mef2D in myogenesis. Here we show that both isoforms of Mef2D bind a largely overlapping subset of genomic loci, yet only the muscle-specific Mef2Da2 isoform can activate the late myogenic gene expression program. This differential ability to activate transcription is modulated by PKA signaling where Mef2Da1 is efficiently phosphorylated by the kinase to enhance its association with repressive HDAC-deacetylase complexes. In contrast, alternate exon usage in Mef2Da2 renders the protein resistant to PKA phosphorylation, allowing it to interact with transcriptionally permissive Ash2L-trithorax complex. Our findings support a model wherein alternative exon usage allows Mef2D to transition from a repressor to activator in a myogenic environment rich in PKA activity. Thus we have identified a novel paradigm in which a ubiquitously expressed transcription factor has evolved to undergo tissue-specific alternative exon usage to permit the proper temporal activation of a gene expression program during differentiation. ChIP-Seq profiling of Mef2Da1 and Mef2Da2 isoforms generated by alternate splicing
2013-06-01 | E-GEOD-43223 | biostudies-arrayexpress
Project description:Changes in alternative splicing are associated with several pathological conditions, including cancer. Microarrays strategies, which allow for the characterization of thousands of alternative splice forms in a single test, can be applied to identify differential alternative splicing events. In this study, a novel splice array platform was developed, including the design of a high-density oligonucleotide array, a labeling procedure, and an algorithm to identify splice events. The array consists of exon probes and thermodynamically balanced junction probes. Suboptimal probes are tagged and considered in the final analysis. An unbiased labeling protocol was developed using random primers. The algorithm used to distinguish changes in expression from changes in splicing was calibrated using internal non-spliced control sequences. The performance of this splice array was first validated with artificial constructs for CDC6, VEGF, and PCBP4 isoforms. The platform was then applied to the analysis of differential splice forms for 8000 genes in lung cancer samples compared to matched normal lung tissue. The expression of lung cancer-associated splice isoforms was validated by RT-PCR. Overexpression of splice isoforms was identified for genes encoding CEACAM1, FHL-1, MLPH, and SUSD2. None of these splicing isoforms had been previously associated with lung cancer. In conclusion, this highly accurate methodology enables the detection of alternative splicing events in complex biological samples, providing a powerful tool to identify novel diagnostic and prognostic biomarkers for cancer and other pathologies.
2009-10-06 | GSE18346 | GEO
Project description:mRNA splicing enlarges the diversity of the protein repertoire, mainly through alternative exon retention or skipping. Although non-canonical splicing variants that exonize intronic regions were recently identified at the mRNA level, their contribution to the cellular proteome remains unclear. Here, we describe a population of 1300 unannotated protein isoforms generated by non-canonical splicing between exons and transposable elements (TE) using a combination of transcriptome assembly, ribosome profiling, and mass spectrometry. Despite being shorter and expressed at lower levels, their translation efficiency is similar to that of canonical isoforms, and they are shared between individuals. Functional analyses of 5 different non-canonical isoforms show stable expression, specific intracellular localization, and modified functions, as compared to the corresponding canonical isoforms. Non-canonical isoforms derive mainly from evolutionarily ancient genes and are a preferential source of alternative splicing upon which natural selection can act. We conclude that recently exonized TE isoforms are potentially functional and represent a diversity reservoir of novel protein isoforms.
2024-12-12 | GSE234223 | GEO
Project description:Thousands of human genes contain introns ending in NAGNAG motifs (N any nucleotide), where both NAGs can function as 3' splice sites, yielding isoforms differing by inclusion/exclusion of just three bases. However, the functional importance of NAGNAG alternative splicing is highly controversial. Using very deep RNA-Seq data from sixteen human and eight mouse tissues, we found that approximately half of alternatively spliced NAGNAGs undergo tissue-specific regulation and that regulated events have been selectively retained: alternative splicing of strongly tissue-specific NAGNAGs was ten times as likely to be conserved between species as for non-tissue-specific events. Further, alternative splicing of human NAGNAGs was associated with an order of magnitude increase in the frequency of exon length changes at orthologous mouse/rat exon boundaries, suggesting that NAGNAGs accelerate exon evolution. Together, our analyses show that NAGNAG alternative splicing constitutes a major generator of tissue-specific proteome diversity and accelerates evolution of proteins at exon-exon boundaries. mRNA-Seq of sixteen human and eight mouse tissues. Supplementary files: human.nagnag.junctions.gff and mouse.nagnag.junctions.gff are the annotation files (in GFF3 format) corresponding to the 'bwtout' mapped reads files linked to the Sample records. Raw data files provided for Samples GSM742937-GSM742952 only.
2012-01-05 | E-GEOD-30017 | biostudies-arrayexpress
Project description:Human ZRANB2 mRNA is alternatively spliced to give two variants with different 3M-bM-^@M-^Y ends. Both isoforms are present in the nucleus of human cells. ZRANB2 binds to mRNA, as well as the essential splicing factors U170K and U2AF35, and the novel splicing component SFRS17A (formerly known as XE7). It has been shown to alter splicing patterns of Tra2M-NM-21 minigene primary transcripts in a dose-dependent manner. It is still unclear what role ZRANB2 plays in the regulation of alternative splicing. To determine the endogenous transcripts that are targeted by ZRANB2 at the genome wide level, we decided to perform exon microarray studies and analyzed the suitability of this method to examine splicing differences in human cells overexpressing a splicing factor. GFP-ZRANB2 construct containing isoform 2 (short form, SF) of ZRANB2 was used. This construct includes exon 1 through to alternative exon 10. Isoform 2 was chosen since it has been shown previously to affect alternative splicing of a Tra2M-NM-21 minigene. HeLa cells were transfected with GFP-ZRANB2, control vector GFP or were left untransfected. RNA was extracted using a Qiagen RNA extraction kit. Experiments were run in 5 replicates.
2012-12-15 | E-GEOD-32932 | biostudies-arrayexpress
Project description:Alternative splicing increases the diversity of transcriptomes and proteomes in metazoans. The extent to which alternative splicing is active and functional in unicellular organisms is less understood. Here we exploit a single-molecule long-read sequencing technique and develop a computational tool, SpliceHunter, to characterize the transcriptome in the meiosis of fission yeast. We reveal 17017 alternative splicing events in 19741 novel isoforms at different stages of meiosis, including antisense and read-through transcripts. Intron retention is the major type of alternative splicing, followed by “alternate intron in exon”. 887 novel transcription units are detected; 60 of the predicted proteins show homology in other species and form theoretical stable structures. We compare the dynamics of novel isoforms based on the number of supporting full-length reads with those of annotated isoforms and explore the translational capacity and quality of novel isoforms. The evaluation of these factors indicates that the majority of novel isoforms are unlikely to be both condition-specific and translatable but the possibility of functional novel isoforms is not excluded. Together, this study highlights the diversity and dynamics at the isoform level in the sexual development of fission yeast.
2016-11-10 | GSE79802 | GEO
Project description:Both epigenetic and splicing regulation contribute to tumor progression, but the potential links between these two levels of gene-expression regulation in pathogenesis are not well understood. Here, we report that the mouse and human RNA helicases ddx17 and ddx5 contribute to tumor-cell invasiveness by regulating alternative splicing of several DNA- and chromatin-binding factors, including the macroH2A1 histone. We show that macroH2A1 splicing isoforms differentially regulate the transcription of a set of genes involved in redox metabolism. In particular, the SOD3 gene that encodes the extracellular superoxide dismutase and plays a part in cell migration is regulated in an inverse manner by macroH2A1 splicing isoforms. These findings reveal a new regulatory pathway in which splicing factors control the expression of histone-variant isoforms that in turn drive a transcription program to switch tumor cells to an invasive phenotype. We analyzed 4T1 cells depleted or not for ddx5 and ddx17 RNA helicases using the Affymetrix Human Exon 1.0 ST platform. Array data was processed by Affymetrix Exon Array Computational Tool. Four techinical replicates were performed. We analyzed 4T1 cells depleted for ddx5 and ddx17 RNA helicases and macroH2A1.1 or macroH2A1.2 using the Affymetrix Human Exon 1.0 ST platform. Array data was processed by Affymetrix Exon Array Computational Tool. Three techinical replicates were performed.
2012-09-11 | E-GEOD-40737 | biostudies-arrayexpress
Project description:Alternative pre-mRNA splicing is a prevalent mechanism in mammals that promotes proteomic diversity, including expression of cell-type specific protein isoforms. We characterized a role for RBM38 (RNPC1) in regulation of alternative splicing during late erythroid differentiation. We used an affymetrix human exon junction (HJAY) splicing microarray to identify a panel of RBM38-regulated alternatively spliced transcripts. Using microarray databases, we noted high RBM38 expression levels in CD71+ erythroid cells and thus chose to examine RBM38 expression during erythroid differentiation of human hematopoietic stem cells, detecting enhanced RBM38 expression during late erythroid differentiation. In differentiated erythroid cells, we validated a subset of RBM38-regulated splicing events and determined that RBM38 regulates activation of Protein 4.1R (EPB41) exon 16 during late erythroid differentiation. Using Epb41 minigenes, Rbm38 was found to be a robust activator of exon 16 splicing. To further address the mechanism of RBM38-regulated alternative splicing, a novel mammalian protein expression system, followed by SELEX-Seq, was used to identify a GU-rich RBM38 binding motif. Lastly, using a tethering assay, we determined that RBM38 can directly activate splicing when recruited to a downstream intron. Together, our data support the role of RBM38 in regulating alternative splicing during erythroid differentiation. siRNA knockdown of RBM38 was perfomed in human MCF-7 breast cancer cells. The efficiency of RBM38 knockdown was monitored by western blot using an RBM38 antibody (Santa Cruz Biotechnology, SC-85873). We conducted HJAY exon and exon junction array profiling on RNAs from four siRBM38 treated MCF-7 samples vs. four sicontrol treated MCF-7 samples Control / knockdown comparison.
2013-07-29 | E-GEOD-49293 | biostudies-arrayexpress