CircRNAs microarray analysis in colorectal caner tissues
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE172229 | GEO | 2021/04/17
REPOSITORIES: GEO
Similar Datasets
Project description:Circular RNAs (circRNAs) are covalently closed non-coding RNAs lacking the 5’ cap and the poly-A tail. Nevertheless, it has been demonstrated that certain circRNAs can undergo active translation. Therefore, aberrantly expressed circRNAs in human cancers could be an unexplored source of tumor-specific antigens, potentially mediating anti-tumor T cell responses. This study presents an immunopeptidomics workflow with a specific focus on generating a circRNA-specific protein fasta reference. The main goal of this workflow is to streamline the process of identifying and validating human leukocyte antigen (HLA) bound peptides potentially originating from circRNAs. We increased the analytical stringency of our workflow by retaining peptides identified independently by two mass spectrometry search engines and/or by applying a group-specific FDR for canonical-derived and circRNA-derived peptides. A subset of circRNA-derived peptides specifically encoded by the region spanning the back-splice junction (BSJ) were validated with targeted MS, and with direct Sanger sequencing of the respective source transcripts. Our workflow identified 54 unique BSJ-spanning circRNA-derived peptides in the immunopeptidome of melanoma and lung cancer samples. Our novel approach enlarges the catalog of source proteins that can be explored for immunotherapy.
2024-03-20 | PXD043989 | Pride
Project description:The objective of this study was to identify and investigate the roles of circRNAs in GDM. In the current study, placental circRNA expression profiles of normal controls and GDM patients were analyzed using high-throughput sequencing. Bioinformatics analysis identified a total of 4955 circRNAs, of which 37 circRNAs were significantly deregulated in GDM placentas compared with NC placentas. GO and KEGG enrichment analyses demonstrated that metabolic process-associated terms and metabolic pathways that may be related to GDM were significantly enriched. The biological characteristics of placenta-derived circRNAs, such as their stability and RNase R resistance, were also validated.Our study indicates that aberrant expression of circRNAs may play roles in autophagy in GDM placentas, providing new insights into GDM.
2022-11-23 | GSE206041 | GEO
Project description:Epstein-Barr virus (EBV) and Kaposi’s sarcoma herpesvirus (KSHV) cause ~2% of all human cancers. RNase R-resistant RNA sequencing revealed that both gammaherpesviruses encode multiple, uniquely stable, circular RNAs (circRNA). EBV abundantly expressed both exon-only and exon-intron circRNAs from the BART locus (circBARTs) formed from a spliced BART transcript and excluding the EBV miRNA region. CircBARTs were expressed in all verified EBV latency types, including EBV- positive post-transplant lymphoproliferative disease (PTLD), Burkitt lymphoma, nasopharyngeal carcinoma, and AIDS-associated lymphoma tissues and cell lines. Only cells infected with the B95-8 EBV strain, with a 12-kb BART locus deletion, were negative for EBV circBARTs. Less abundant levels of EBV circRNAs originating from LMP2 and BHLF1-encoding genes were also identified. CircRNA sequencing of KSHV- infected PEL cells revealed a KSHV-encoded circRNA from the vIRF4 locus (circvIRF4) that was constitutively expressed. In addition, KSHV polyadenylated nuclear (PAN) RNA locus generated a swarm (>100) of multiply backspliced, low-abundance RNase R- resistant circRNAs originating in both sense and antisense directions consistent with a novel hyper-backsplicing mechanism. In EBV and KSHV co-infected cells, exon-only EBV circBARTS were located more in the cytoplasm, whereas the intron-retaining circBARTs were found in the nuclear fraction. KSHV circvIRF4 and circPANs were detected in both nuclear and cytoplasmic fractions. Among viral circRNAs tested, none were found in polysome fractions from KSHV-EBV co-infected BC1 cells although low abundance protein translation from viral circRNAs could not be excluded. CircRNAs are a new class of viral transcripts expressed in gammaherpesvirus-related tumors that might contribute to viral oncogenesis.
2018-07-28 | GSE117798 | GEO
Project description:We determined circRNA abundance in fly Heads and S2 cells by generating and analyzing high-throughput RNA-sequencing libraries prepared from rRNA-depleted RNA. In order to determine whether the observed sequencing reads are due to bona fide circRNAs, we pre-treated the RNA with RNAse-R before the rRNA-depletion procedure. Indeed, most of the identified circRNAs were more enriched in comparison to the canonical mRNA isoforms following the RNAse-R treatment. We compare circRNA levels in wt (Canton S) flies with flies carrying the C4 ("slow polymerase") mutation. 4 samples of Drosophila Canton S and 4 samples of flies carrying the C4 ("slow polymerase") mutation. For each sample, one library was prepared from RNA after RNaseR treatment and the second from RNA with without treatment (mock). RNA library from one Canton Sample was used for stranded libray preprepation.
2014-10-14 | E-GEOD-55872 | biostudies-arrayexpress
Project description:Circular RNAs (circRNAs) are a large class of animal RNAs. To investigate possible circRNA functions, it is important to understand circRNA biogenesis. Besides human Alu repeats, sequence features that promote exon circularization are largely unknown. We experimentally identified new circRNAs in C. elegans. Reverse complementary sequences between introns bracketing circRNAs were significantly enriched compared to linear controls. By scoring the presence of reverse complementary sequences in human introns we predicted and experimentally validated novel circRNAs. We show that introns bracketing circRNAs are highly enriched in RNA editing or hyper-editing events. Knockdown of the double-strand RNA editing ADAR1 enzyme significantly and specifically up-regulated circRNA expression. Together, our data support a model of animal circRNA biogenesis in which competing RNA:RNA interactions of introns form larger structures which promote circularization of embedded exons, while ADAR1 antagonizes circRNA expression by melting stems within these interactions. Thus, we assign a new function to ADAR1. Examination of 12 samples in different stages of C.elegans development.
2015-01-06 | E-GEOD-63823 | biostudies-arrayexpress
Project description:Viral noncoding RNAs have acquired increasing prominence as important regulators of infection and mediators of pathogenesis. Circular RNAs (circRNAs) generated by backsplicing events have been identified in several oncogenic human DNA viruses. Here, we show that Merkel cell polyomavirus (MCV), the etiologic cause of ~80% of Merkel cell carcinomas (MCCs), also expresses circular RNAs. By RNase R-resistant RNA sequencing, four putative circRNA backsplice junctions (BSJs) were identified from the MCV early region (ER). The most abundantly expressed MCV circRNA, designated circMCVT, is generated through backsplicing of all of ER exon II to form a 762-nucleotide (nt) circular RNA molecule. Curiously, circMCV-T, as well as two other less abundantly expressed putative MCV circRNAs, overlaps in a complementary fashion the MCV microRNA (miRNA) locus that encodes MCV-miR-M1. circMCV-T is consistently detected in concert with linear T antigen transcripts throughout infection, suggesting a crucial role for this RNA molecule in the regulatory functions of the early region, known to be vital for viral replication. Knocking out the hairpin structure of MCV-miR-M1 in genomic early region expression constructs and using a new high-efficiency, recombinase-mediated, recircularized MCV molecular clone demonstrates that circMCV-T levels decrease in the presence of MCV-miR-M1, underscoring the interplay between MCV circRNA and miRNA. Furthermore, circMCV-T partially reverses the known inhibitory effect of MCV-miR-M1 on early gene expression. RNase R-resistant RNA sequencing of lytic rat polyomavirus 2 (RatPyV2) identified an analogously located circRNA, stipulating a crucial, conserved regulatory function of this class of RNA molecules in the family of polyomaviruses.
2020-12-07 | GSE162627 | GEO
Project description:In platelets, splicing and translation occur in the absence of a nucleus. However, the integrity and stability of mRNAs derived from megakaryocyte progenitor cells remain poorly quantified on a transcriptome-wide level. As circular RNAs (circRNAs) are resistant to degradation by exonucleases, their abundance relative to linear RNAs can be used as a surrogate marker for mRNA stability in the absence of transcription. Here we show that circRNAs are enriched in human platelets 17-188 fold relative to nucleated tissues, and 14-26 fold relative to samples digested with RNAseR to selectively remove linear RNA. We compare RNAseq read depths inside and outside circRNAs to provide in silico evidence of transcript circularity, show that exons within circRNAs are enriched ~13X in platelets relative to nucleated tissues, and identify 3162 genes significantly enriched for circRNAs including some where all RNAs appear to be derived from circular molecules. We also confirm that this is a feature of other anucleate cells through transcriptome sequencing of mature erythrocytes, demonstrate that circRNAs are not enriched in megakaryocytes, and that linear RNAs decay more rapidly than circRNAs in platelet preparations. Collectively, these results suggest that circulating platelets have lost on aveage over 90% of their progenitor mRNAs, and that translation in platelets occurrs against the backdrop of a highly degraded transcriptome. Finally, we find that transcripts classified as products of reverse transcriptase template switching are both enriched in platelets and resistant to decay, countering the recent suggestion that up to 50% of rearranged RNAs are artefacts. A single rRNA depleted total RNA sample was sequenced. This together with 25 publicly available rRNA depleted total RNA samples (including 3 from platelets) were analysed using PTESFinder v 1 (http://sourceforge.net/projects/ptesfinder-v1/) to identify back-splice junctions, characteristic of circRNA transcripts. The contribution of circRNA producing exons was analysed on a gene by gene basis as follows: All circRNA transcripts identified in any sample were first pooled to define exons which can contribute to circRNA generation using custom scripts (available on request). For each sample, expression estimates (RPKMI) across all circRNA producing exons were computed for each locus using the total size of exons (in bp) and the read counts mapping to them. Similarly, total size and exonic read counts for exons for which no circRNA were detected in any sample were used to compute expression estimates (RPKME) for non-circRNA producing exons for each locus. Abundance ratios (RPKMI/RPKME and RPKMI/RPKMI+RPKME) were calculated and compared between Platelets and human tissues using Wilcoxon signed-rank test. Please note that the '25sample_info_accn_no.txt' contains the accession numbers and tissue/cell type information for 25 samples analyzed together.
2015-12-12 | E-GEOD-69192 | biostudies-arrayexpress
Project description:Objective: As one kind of novel non-coding RNA with high stability and conservatism, circular RNAs (circRNAs) are involved in different biological processes. Although growing evidence has supported the important role of circRNAs in renal diseases, the specific mechanism still remains unknown in neonatal acute kidney injury (AKI). Methods: High throughput sequencing analysis was applied to investigate the expression patterns of circRNAs in the comparison between hypoxia induced AKI neonates and controls. Then, bioinformatics analysis was conducted to predict the function of differentially expressed circRNAs and construct the network of circRNA-miRNA interaction. Results: (1) We identified 296 differentially expressed circRNAs (circRNAs with Fold change > 2 and P value < 0.05). Of them, 184 circRNAs were markedly up-regulated and 112 were significantly down-regulated in the AKI group. (2) Bioinformatics analysis indicated that the parental genes of the differentially expressed circRNAs were predominantly implicated in the cell and cell part, cellular process and cancer pathways. Conclusion: This study could contribute to future research of circRNAs in the pathogenesis of neonatal AKI and facilitate the identification of novel therapeutic targets of circRNAs.
2023-01-11 | GSE222578 | GEO
Project description:Purpose: With the advent of human genome sequencing project, circRNAs attracted widespread attention in cancer research due to its stable ring structure. Our aim was to identify differentially expressed circRNAs in GC and explore their potential roles in GC diagnosis and treatment. Methods: Total RNA from tissues was isolated by Hipure Total RNA Mini Kit (Magen, Germany). Qubit 3.0 Fluorometer (Invitrogen, Carlsbad, California) was used for RNA concentration measurement while Agilent 2100 Bioanalyzer (Applied Biosystems, Carlsbad, CA) for RNA integrity estimation. A RIN value over 7.0 was considered eligible. RNA-seq library was prepared with approximately 2μg of total RNA using KAPA RNA HyperPrep Kit with RiboErase (HMR) for Illumina® (Kapa Biosystems, Inc., Woburn, MA). Briefly, total RNA was incubated at 37 °C for 30 min with 10 units RNase R (Epicentre Technologies, Madison, USA) after removing ribosomal RNA. Next, the ribominus RNase R (+) RNAs was fragmented and then first strand and directional second strand synthesis were performed. Then the A tailing and adapter ligation were performed with the purified cDNA. Finally, the purified, adapter-ligated DNA was amplified. Each library was diluted to 10 nM and pooled equimolar prior to clustering. Paired-End (PE150) sequencing was performed on all samples. Results: A total of 25,303 circRNA targets, including 20,036 known circRNAs and 5,267 uncharacterized circRNAs, were detected and defined. Among them, there were 2,007 circRNAs with statistically significant differences in expression in GC tissues, in which fold changes>2.0 and P<0.05 were identified.
2019-06-16 | GSE131414 | GEO
Project description:High-throughput RNA sequencing methods coupled with specialized bioinformatic analyses have recently uncovered tens of thousands of unique circular (circ)RNAs, but their complete sequences, genes of origin, and functions are largely unknown. Given that circRNAs lack free ends and are thus relatively stable, their association with microRNAs (miRNAs) and RNA-binding proteins (RBPs) can influence gene expression programs. While exoribonuclease treatment is widely used to degrade linear RNAs and enrich circRNAs in RNA samples, it does not efficiently eliminate linear RNAs. Here, we describe a novel method for the isolation of highly pure circRNA populations involving RNase R treatment followed by Polyadenylation and poly(A)+ RNA Depletion (RPAD), which removes linear RNA to near completion. High-throughput sequencing of RNA prepared using RPAD from human cervical carcinoma HeLa cells and mouse C2C12 myoblasts led to two surprising discoveries: (1) many circRNA isoforms share an identical backsplice sequence but have different body sizes and sequences, and (2) thousands of novel intronic circular RNAs (IcircRNAs) are expressed in cells, including many IcircRNAs that do not follow gt/ag splicing patterns. In sum, isolating high-purity circRNAs using the RPAD method can enable quantitative and qualitative analyses of circRNA types and sequence composition, paving the way for the elucidation of circRNA functions.
2017-05-03 | GSE92632 | GEO