Pathways for macrophage uptake of cell-free circular RNAs
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE264160 | GEO | 2024/08/01
REPOSITORIES: GEO
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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:Circular RNAs (circRNAs) are an endogenous class of animal RNAs. Despite their abundance, their function and expression in the nervous system are unknown. Therefore, we sequenced RNA from different brain regions, primary neurons, isolated synapses, as well as during neuronal differentiation. Using these and other available data, we discovered and analyzed thousands of neuronal human and mouse circRNAs. circRNAs were extraordinarily enriched in the mammalian brain, well conserved in sequence, often expressed as circRNAs in both human and mouse, and sometimes even detected in Drosophila brains. circRNAs were overall upregulated during neuronal differentiation, highly enriched in synapses, and often differentially expressed compared to their mRNA isoforms. circRNA expression correlated negatively with expression of the RNA-editing enzyme ADAR1. Knockdown of ADAR1 induced elevated circRNA expression. Together, we provide a circRNA brain expression atlas and evidence for important circRNA functions and values as biomarkers. To assess circRNA expression in mammalian brain, we sequenced and analyzed mouse brain regions (hippocampus, cerebellum, prefrontal cortex and olfactory bulb), various neuronal differentiation (mouse P19 and human SH-SY5Y cells) and maturation (mouse cortical neurons) stages, and subcellular compartments in mouse (synaptoneurosomal fraction, cytoplasmic fraction, whole brain lysate).
2015-04-24 | E-GEOD-65926 | biostudies-arrayexpress
Project description:The human genome encodes tens of thousands circular RNAs (circRNAs) whose levels correlate with many disease states. While studies have focused on the non-coding functions of circRNAs, emerging evidence suggests that a handful of circRNAs encode proteins. Translation canonically starts by recognition of mRNA 5’cap and scanning to the start codon; how circRNA translation initiates remains unclear. Here, we developed a high-throughput screen to systematically identify and quantify RNA sequences that can direct circRNA translation. We identify and validate over 17,000 circRNA internal ribosome entry sites (IRES) and reveal that 18S rRNA complementarity and a structured RNA element on the IRES are important for facilitating circRNA cap-independent translation. With genomic and peptidomic analyses of the IRES, we identified nearly 1,000 putative endogenous protein-coding circRNAs and hundreds of translational units encoded by these circRNAs. We further characterized circFGFR1p, a protein encoded by circFGFR1, functions as a negative regulator of FGFR1 to suppress cell growth under stress conditions. The circRNA proteome may be important links among circRNA, biological control, and disease.
2021-08-23 | PXD024993 | Pride
Project description:The human genome encodes tens of thousands circular RNAs (circRNAs) whose levels correlate with many disease states. While studies have focused on the non-coding functions of circRNAs, emerging evidence suggests that a handful of circRNAs encode proteins. Translation canonically starts by recognition of mRNA 5’cap and scanning to the start codon; how circRNA translation initiates remains unclear. Here, we developed a high-throughput screen to systematically identify and quantify RNA sequences that can direct circRNA translation. We identify and validate over 17,000 circRNA internal ribosome entry sites (IRES) and reveal that 18S rRNA complementarity and a structured RNA element on the IRES are important for facilitating circRNA cap-independent translation. With genomic and peptidomic analyses of the IRES, we identified nearly 1,000 putative endogenous protein-coding circRNAs and hundreds of translational units encoded by these circRNAs. We further characterized circFGFR1p, a protein encoded by circFGFR1, functions as a negative regulator of FGFR1 to suppress cell growth under stress conditions. The circRNA proteome may be important links among circRNA, biological control, and disease.
2021-08-26 | PXD025203 | Pride
Project description:The human genome encodes tens of thousands circular RNAs (circRNAs) whose levels correlate with many disease states. While studies have focused on the non-coding functions of circRNAs, emerging evidence suggests that a handful of circRNAs encode proteins. Translation canonically starts by recognition of mRNA 5’cap and scanning to the start codon; how circRNA translation initiates remains unclear. Here, we developed a high-throughput screen to systematically identify and quantify RNA sequences that can direct circRNA translation. We identify and validate over 17,000 circRNA internal ribosome entry sites (IRES) and reveal that 18S rRNA complementarity and a structured RNA element on the IRES are important for facilitating circRNA cap-independent translation. With genomic and peptidomic analyses of the IRES, we identified nearly 1,000 putative endogenous protein-coding circRNAs and hundreds of translational units encoded by these circRNAs. We further characterized circFGFR1p, a protein encoded by circFGFR1, functions as a negative regulator of FGFR1 to suppress cell growth under stress conditions. The circRNA proteome may be important links among circRNA, biological control, and disease.
2021-08-23 | PXD025235 | Pride
Project description:The human genome encodes tens of thousands circular RNAs (circRNAs) whose levels correlate with many disease states. While studies have focused on the non-coding functions of circRNAs, emerging evidence suggests that a handful of circRNAs encode proteins. Translation canonically starts by recognition of mRNA 5’cap and scanning to the start codon; how circRNA translation initiates remains unclear. Here, we developed a high-throughput screen to systematically identify and quantify RNA sequences that can direct circRNA translation. We identify and validate over 17,000 circRNA internal ribosome entry sites (IRES) and reveal that 18S rRNA complementarity and a structured RNA element on the IRES are important for facilitating circRNA cap-independent translation. With genomic and peptidomic analyses of the IRES, we identified nearly 1,000 putative endogenous protein-coding circRNAs and hundreds of translational units encoded by these circRNAs. We further characterized circFGFR1p, a protein encoded by circFGFR1, functions as a negative regulator of FGFR1 to suppress cell growth under stress conditions. The circRNA proteome may be important links among circRNA, biological control, and disease.
2021-08-25 | PXD025233 | Pride
Project description:Circular RNAs (circRNAs), formed by the atypical head-to-tail splicing of exons, have re-emerged as a potentially interesting RNA species given recent reports of a surprising diversity and abundance of circRNA in organisms ranging from worm to human. Here, using deep RNA sequencing, we profiled different RNA species in mouse and observed that circRNAs are significantly enriched in neural tissue, relative to other tissues. Using PacBio sequencing, we determined, for the first time, the circular structure of this population of circRNAs as well as their full-length sequences. We discovered that a disproportionate fraction of the brain circRNA population is derived from host genes that code for synaptic proteins. Moreover, based on the separate profiling of the RNAs localized in neuronal cell bodies and neuropil (enriched in axons and dendrites), we found that, on average, circular RNAs are more enriched in the neuropil than their host gene mRNA isoforms. Using high resolution in situ hybridization we, for the first time, directly visualized circRNA punctae in the dendrites of neurons. The host gene origin and location of the circRNA in neurons suggest the possibility that circRNAs might participate in the regulation of synaptic function and plasticity. Consistent with this idea, we observed via profiling at different developmental stages, that the abundance of many circular RNAs changes abruptly at a time corresponding to synaptogenesis. In addition, following a homeostatic downscaling of neuronal activity many circRNAs exhibit significant up or down-regulation. These data indicate that brain circRNAs are positioned to respond to and regulate synaptic function. Circular RNA profiling in 13 different samples in mice and four samples in rat, using Illumina sequencing
2015-02-25 | E-GEOD-61991 | biostudies-arrayexpress
Project description:Objective: Bladder outlet obstruction (BOO) is a common urologic disease associated with poorly understood molecular mechanisms. This study aimed to investigate the possible involvements of circRNAs (circular RNAs) and circRNA-encoded proteins in BOO development. Methods: The rat BOO model was established by the partial bladder outlet obstruction surgery. Differential expression of circRNA and protein profiles were characterized by deep RNA sequencing and iTRAQ quantitative proteomics respectively. Novel proteins encoded by circRNAs were predicted through ORF (open reading frame) selection using the GETORF software and verified by the mass spectrometry in proteomics, combined with the validation of their expressional alterations by quantitative RT-PCR. Results: Totally 3051 circRNAs were differentially expressed in bladder tissues of rat BOO model with widespread genomic distributions, including 1414 up-regulated and 1637 down-regulated circRNAs. Our following quantitative proteomics revealed significant changes of 85 proteins in rat BOO model, which were enriched in multiple biological processes and signaling pathways such as the PPAR and Wnt pathways. Among them, 21 differentially expressed proteins were predicted to be encoded by circRNAs and showed consistent circRNA and protein levels in rat BOO model. The expression of five protein-encoding circRNA were further validated by quantitative RT-PCR and mass spectrometry. Conclusion: The circRNA and protein profiles were substantially altered in rat BOO model, with great expressional changes of circRNA-encoded novel proteins.
2022-02-22 | PXD029337 | Pride
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:Arraystar Human circRNA Microarray is designed for the global profiling of human circRNAs. In this study, we applied a circRNA microarray to screen the potential biomarker for HCC. 20 samples extracted from plasma samples including HCC group before operation, and after operation, CH group and control group. Each group contained five samples.
2021-03-02 | E-MTAB-8799 | biostudies-arrayexpress