Identification of pathological pathways centered on circRNA dysregulation initiated at a critical window of Alzheimer’s disease progression
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE236683 | GEO | 2024/10/22
REPOSITORIES: GEO
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Project description:Background Circular RNAs (circRNAs) are highly stable regulatory molecules, often accumulated in the mammalian brain and thought to serve as “memory molecules” that govern the long process of aging. Mounting evidence demonstrated circRNA dysregulation in postmortem cortical regions of Alzheimer’s disease (AD) patients. However, whether and how circRNA dysregulation underlies AD progression remains unexplored. Methods Poly(A)-tailing/RNase R digestion was coupled with our recently published computational algorithm CARP to identify genome-wide dysregulation of circRNAs and their downstream pathways in the 5xFAD mouse cerebral cortex between 5- and 7-month of age, a critical window that marks the transition from reversible to irreversible pathogenic progression. Irreversibly dysregulated circRNAs and pathways in 5xFAD cortex were systematically compared with a large human AD cohort study. A top ranked circRNA conserved and commonly affected in AD patients and 5xFAD mice was depleted in cultured cells to confirm its causal roles in AD-relevant molecular and cellular changes. Results We discovered genome-wide circRNA alterations specifically in the 5xFAD cortex associated with AD progression and found numerous circRNAs also consistently affected in AD patient postmortem cortical areas. Among such circRNAs, circGigyf2 showed the highest net reduction starting from 7-month of age, which is highly conserved and negatively correlated with human AD severity. Mechanistically, we found multiple AD-affected splicing factors that are essential for circGigyf2 biogenesis. Functionally, we identified and experimentally validated the conserved roles of circGigyf2 in sponging AD-relevant miRNAs and AD-associated RNA binding proteins (RBPs) including the cleavage and polyadenylation factor 6 (CPSF6). CircGigyf2 downregulation in AD exert silencing activities of its sponged miRNAs and aberrantly enhanced the polyadenylation efficiency of many CPSF6 targets. These post-transcriptionally tuned mRNAs by circGigyf2 were enriched in apoptotic pathways. Furthermore, circGigyf2 depletion in a mouse immortalized neuronal cell line dysregulated circGigyf2-miRNA and circGigyf2-CPSF6 axes and potentiated neuronal responses to apoptotic insults, which strongly support the causative role of circGigyf2 deficiency in AD disease progression. Conclusions Together, our results unveiled pathological alterations of the brain circRNA landscape associated with irreversible disease stage in an AD mouse model and identified novel molecular mechanisms underlying dysregulation of conserved circRNA pathways that contribute to AD pathogenesis.
2024-10-22 | GSE272745 | GEO
Project description:Background Circular RNAs (circRNAs) are highly stable regulatory molecules, often accumulated in the mammalian brain and thought to serve as “memory molecules” that govern the long process of aging. Mounting evidence demonstrated circRNA dysregulation in postmortem cortical regions of Alzheimer’s disease (AD) patients. However, whether and how circRNA dysregulation underlies AD progression remains unexplored. Methods Poly(A)-tailing/RNase R digestion was coupled with our recently published computational algorithm CARP to identify genome-wide dysregulation of circRNAs and their downstream pathways in the 5xFAD mouse cerebral cortex between 5- and 7-month of age, a critical window that marks the transition from reversible to irreversible pathogenic progression. Irreversibly dysregulated circRNAs and pathways in 5xFAD cortex were systematically compared with a large human AD cohort study. A top ranked circRNA conserved and commonly affected in AD patients and 5xFAD mice was depleted in cultured cells to confirm its causal roles in AD-relevant molecular and cellular changes. Results We discovered genome-wide circRNA alterations specifically in the 5xFAD cortex associated with AD progression and found numerous circRNAs also consistently affected in AD patient postmortem cortical areas. Among such circRNAs, circGigyf2 showed the highest net reduction starting from 7-month of age, which is highly conserved and negatively correlated with human AD severity. Mechanistically, we found multiple AD-affected splicing factors that are essential for circGigyf2 biogenesis. Functionally, we identified and experimentally validated the conserved roles of circGigyf2 in sponging AD-relevant miRNAs and AD-associated RNA binding proteins (RBPs) including the cleavage and polyadenylation factor 6 (CPSF6). CircGigyf2 downregulation in AD exert silencing activities of its sponged miRNAs and aberrantly enhanced the polyadenylation efficiency of many CPSF6 targets. These post-transcriptionally tuned mRNAs by circGigyf2 were enriched in apoptotic pathways. Furthermore, circGigyf2 depletion in a mouse immortalized neuronal cell line dysregulated circGigyf2-miRNA and circGigyf2-CPSF6 axes and potentiated neuronal responses to apoptotic insults, which strongly support the causative role of circGigyf2 deficiency in AD disease progression. Conclusions Together, our results unveiled pathological alterations of the brain circRNA landscape associated with irreversible disease stage in an AD mouse model and identified novel molecular mechanisms underlying dysregulation of conserved circRNA pathways that contribute to AD pathogenesis.
2024-10-22 | GSE272744 | GEO
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: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), a noncoding RNA class originating from alternative splicing, are highly abundant in neural tissues and were shown to regulate gene expression e.g. by interacting with microRNAs and RNA-binding proteins. Neuroblastoma is an embryonal neoplasia, which arises from undifferentiated neural crest cells. Here, we aimed to explore, whether circRNAs influence the pathogenesis of high-risk neuroblastoma. We performed whole-transcriptome sequencing of 104 primary neuroblastoma samples of all risk-groups and identified 5,203 unique circRNAs involving 2,302 genes. Candidate circRNA expression did not correlate with host gene expression, indicating independent regulatory mechanisms. circRNAs were significantly downregulated in the MYCN-amplified high-risk tumors. These findings were independently reproduced in a tetracycline-inducible MYCN-overexpression system based on a non MYCN-amplified neuroblastoma cell line, suggesting that MYCN drives this global circRNA repression. We identified the RNA helicase DHX9 as a mediator of this global suppressive effect of MYCN on circRNAs. Comparing our RNA sequencing data with other cancers and controls revealed a circRNA subset specifically upregulated in neuroblastoma that included a circRNA derived from the ARID1A tumor suppressor gene. Specific circARID1A knockdown resulted in reduced proliferation, cell numbers and viability, prompted apoptosis and induced a differentiated phenotype. Neither knockdown, nor overexpression of circARID1A influenced ARID1A mRNA and protein levels significantly. To dissect the potential mode of function, we performed a pulldown assay with subsequent mass spectrometry. We identified the RNA-binding protein KHSRP as an interaction partner that participates in the mechanism of action of circARID1A. In summary, this study highlights an important role of circRNAs in neuroblastoma biology and may establish this RNA class as a future therapeutic target and biomarker.
2023-04-06 | PXD026053 | Pride
Project description:Atrial fibrillation (AF) is the most common irregular heart rhythm which influence approximately 1–2% of the general population. As a potential factor for ischemic stroke, AF could also cause heart failure. The mechanisms behind AF pathogenesis are complex and remains elusive. As a new category of non-coding RNAs (ncRNAs), circular RNAs (circRNAs) have been known as the key of developmental processes, regulation of cell function, pathogenesis of heart diseases and pathological responses which could provide novel sight into the pathogenesis of AF. circRNAs function as modulators of microRNAs in cardiac disease. To investigate the regulatory mechanism of circRNA in atrial fibrillation, especially the complex interactions among circRNA, microRNA and mRNA, we collected the heart tissues from three AF patients and three healthy controls and profiled their circRNA expressions with circRNA Microarray. The differentially expressed circRNAs were identified and the biological functions of their interaction microRNAs and mRNAs were analyzed. Our results provided novel insights of the circRNA roles in atrial fibrillation and proposed highly possible interaction mechanisms among circRNAs, microRNAs and mRNAs.
2019-04-06 | GSE129409 | GEO
Project description:This study investigated the pathogenesis of Alzheimer’s disease by analyzing the differential expression of circular RNAs (circRNAs), and their interactions with microRNAs (miRNAs). A circRNA microarray was used to screen expressed circRNAs in peripheral blood leukocytes from three patients with AD and four healthy control participants. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to annotate the functions of the circRNAs. Changes in expression of six circRNAs [0045808/0070162/0001929/0092270/0092222/0092223]) was confirmed by RT-qPCR, of which three (hsa_circ_[0045808/0070162/0092270]) were further verified by RT-qPCR using a large sample of 23 patients with AD and 25 healthy controls. A circRNA-miRNA-mRNA interaction network, constructed using TargetScan, miRanda, and Cytoscape, revealed upregulated (n=311) and downregulated (n=433) circRNAs, whereaswhile 443 circRNAs were downregulated. GO and KEGG analyses associated differentially expressed circRNAs to neurotransmitters, cell senescence, P53, mTOR, and PI3K-AKT. Microarray sample verification using RT-qPCR confirmed the microarray analysis results on changes in the six circRNAs. Contrary to the microarray analysis, large-sample verification of significantly elevated circRNA expression was partially consistent (hsa_circ_0092270), and inconsistent (hsa_circ_0045808, hsa_circ_0070162), with the microarray results. The findings highlight the significance of circRNAs in AD and that hsa_circ_0092270 represents a promising biomarker for future studies.
2022-05-13 | GSE186929 | GEO
Project description:Circular RNAs (circRNA) are special non-coding RNAs. They are widely present, but with unknown functions. Recent studies have shown that many endogenous circRNAs have sponge function to absorb microRNAs. They can regulate target gene mRNA expression and play important roles in many biological processes. However, expression profile and function of circRNAs in human TSCC haven’t been reported. High-throughput sequencing was performed to identify and annotate from three TSCC tissues and adjacent tissues. A separate set (n=20) of human TSCCs and corresponding adjacent tissues were subjected to RT-PCR for validation of circular RNAs expression profile. GO functional analysis, KEGG pathway analysis, and circRNA–microRNA network analysis were also performed to predict the function of circRNA in TSCC.A total of 12,156 circRNAs were identified and annotated, most of the circRNAs were novel (n=6,231) and exonic (62.09%). Statistical analysis revealed 322 differentially expressed (DE) circRNAs. RT-PCR results showed that circRNA expression in TSCC was higher than that in adjacent tissues. GO functional analysis, KEGG pathway analysis, and circRNA–microRNA network analysis all showed that circRNAs correlated with tumor development and progression to a certain extent. The present study is the first to systematically characterize and annotate circRNA expression in TSCC, the majority were novel circRNAs. Some host genes of the DE circRNAs were involved in tumor signaling pathway and had complicated correlations with tumor-relevant microRNAs, indicating that circRNAs might be promoted development and progression of TSCC.
2018-12-31 | GSE118750 | GEO
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.
2021-08-23 | PXD024993 | Pride