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PROVIDER: PRJNA900561 | ENA |
REPOSITORIES: ENA
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Project description:Transposable elements are viewed as ‘selfish genetic elements’, yet they contribute to gene regulation and genome evolution in diverse ways. More than half of the human genome consists of transposable elements. With over 1 million insertions, Alu elements belong to the short interspersed nuclear element (SINE) family of repetitive elements, and with over 1 million insertions they make up more than 10% of the human genome. Despite their abundance and the potential evolutionary advantages they confer, Alu elements can be mutagenic to the host as they can act as splice acceptors, inhibit translation of mRNAs and cause genomic instability. Alu elements are the main targets of the RNA-editing enzyme ADAR and the formation of Alu exons is suppressed by the nuclear ribonucleoprotein HNRNPC, but the broad effect of massive secondary structures formed by inverted-repeat Alu elements on RNA processing in the nucleus remains unknown. Here we show that DHX9, an abundant nuclear RNA helicase, binds specifically to inverted-repeat Alu elements that are transcribed as parts of genes. Loss of DHX9 leads to an increase in the number and amount of circular RNAs, translational repression of reporters containing inverted-repeat Alu elements, and transcriptional rewiring (the creation of mostly nonsensical novel connections between exons) of susceptible loci. Biochemical purifications of DHX9 identify the interferon-inducible isoform of ADAR (p150), but not the constitutively expressed ADAR isoform (p110), as an RNA-independent interaction partner. Co-depletion of ADAR and DHX9 augments the double-stranded RNA accumulation defects, leading to higher levels of circular RNA production, revealing a functional link between these two enzymes. Our work uncovers an evolutionarily conserved function of DHX9. We propose that it acts as a nuclear RNA resolvase that neutralizes the immediate threat posed by transposon insertions and allows these elements to evolve as tools for the post-transcriptional regulation of gene expression. This SuperSeries is composed of the SubSeries listed below.
2017-03-28 | GSE85164 | GEO
Project description:The combination of epigenetic and immunotherapy is emerging as a promising approach for cancer therapy. Derepression of transposable elements (TE) by epigenetic drugs leads to activation of immune response. However, the molecular mechanism of TE regulation by distinct chromatin modifier enzymes (CME) in context of p53 is still elusive. Here, we used FDA-approved epigenetic drugs to systematically inhibit distinct CMEs in p53 wild-type and p53-mutant colorectal, esophageal, and prostate cancer cells. We show that distinct TE subfamilies are derepressed by inhibition of different CMEs in cell type-specific manner. Co-inhibition of DNMT and HDAC (DNMTi-HDACi) had the most consistent effect across cancer types. Loss of p53 results in stronger TE activation and TE-chimeric transcript expression and this effect is largely mediated by the non-genomic actions of p53. Robust immune response elicited by DNMTi-HDACi is due to induced inverted repeat Alu expression concomitant with reduced ADAR1-mediated Alu RNA editing, whereas SETDB1 inhibition activates ADAR1 expression. Collectively, our systematic analyses provide insights for rational use of epigenetic therapies in distinct cancers.
2025-06-16 | GSE254243 | GEO
Project description:Derepression of transposable elements (TE) by epigenetic therapy leads to the activation of immune response in cancer cells. However, the molecular mechanism of TE regulation by distinct chromatin modifier enzymes (CME) in context of p53 is still elusive. Here, we used FDA-approved epigenetic drugs to systematically inhibit distinct CMEs in p53 wild-type and p53-mutant colorectal, esophageal, and prostate cancer cells. We show that distinct TE subfamilies are derepressed by inhibition of different CMEs in cell type-specific manner. Co-inhibition of DNMT and HDAC (DNMTi-HDACi) had the most consistent effect across cancer types. Loss of p53 results in stronger TE activation and TE-chimeric transcript expression and this effect is largely mediated by the non-genomic actions of p53. Robust immune response elicited by DNMTi-HDACi is due to induced inverted repeat Alu expression concomitant with reduced ADAR1-mediated Alu RNA editing. Collectively, our systematic analyses provide insights for rational use of epigenetic therapies in distinct cancers.
2025-06-16 | GSE254242 | GEO
Project description:Derepression of transposable elements (TE) by epigenetic therapy leads to the activation of immune response in cancer cells. However, the molecular mechanism of TE regulation by distinct chromatin modifier enzymes (CME) in context of p53 is still elusive. Here, we used FDA-approved epigenetic drugs to systematically inhibit distinct CMEs in p53 wild-type and p53-mutant colorectal, esophageal, and prostate cancer cells. We show that distinct TE subfamilies are derepressed by inhibition of different CMEs in cell type-specific manner. Co-inhibition of DNMT and HDAC (DNMTi-HDACi) had the most consistent effect across cancer types. Loss of p53 results in stronger TE activation and TE-chimeric transcript expression and this effect is largely mediated by the non-genomic actions of p53. Robust immune response elicited by DNMTi-HDACi is due to induced inverted repeat Alu expression concomitant with reduced ADAR1-mediated Alu RNA editing. Collectively, our systematic analyses provide insights for rational use of epigenetic therapies in distinct cancers.
2025-06-16 | GSE254244 | GEO
Project description:Alu SINEs are the most numerous frequently occurring transcription units in our genomes and possess sequence competence for transcription by RNA Pol III. However, through poorly understood mechanisms, the Alu RNA levels are maintained at very low levels in normal somatic cells with obvious benefits of low rates of Alu retrotransposition and energy-economical deployment of RNA Pol III to the tRNA genes which share promoter structure and polymerase requirements with Alu SINEs. Using comparative ChIP sequencing, we unveil that a repeat binding protein, CGGBP1, binds to the transcriptional regulatory regions of Alu SINEs thereby impeding Alu transcription by inhibiting RNA Pol III recruitment. We show that this Alu-silencing depends on growth factor stimulation of cells and subsequent tyrosine phosphorylation of CGGBP1. Importantly, CGGBP1 ensures a sequence-specific discriminative inhibition of RNA Pol III activity at Alu promoters, while sparing the structurally similar tRNA promoters. Our data suggest that CGGBP1 contributes to growth-related transcription by preventing the hijacking of RNA Pol III by Alu SINEs. Examination of one DNA binding protein in two different conditions of treatment.
2015-04-29 | E-GEOD-53571 | biostudies-arrayexpress
Project description:Biogenesis of circular RNA usually involves a backsplicing reaction where the downstream donor site is ligated to the upstream acceptor site by the spliceosome. For this reaction to occur, it is hypothesized that these two sites must be in proximity. Inverted repeat sequences, such as Alu elements, in the upstream and downstream introns are predicted to base-pair and represent one mechanism for inducing proximity. Here, we investigate the pre-mRNA structure of the human HIPK3 gene, specifically exon 2, which forms a circular RNA via backsplicing. We leverage multiple chemical probing techniques, including the recently developed SHAPE-JuMP strategy, to characterize both secondary and tertiary interactions in the pre-mRNA that govern backsplicing. Our data confirm that the antisense Alu elements, AluSz(-) and AluSq2(+) in the upstream and downstream introns, form a highly-paired interaction. Circularization requires formation of long-range Alu-mediated base pairs but does not require the full-length AluSq2(+). In addition to confirming long-range base pairs, our SHAPE-JuMP data also identified multiple long-range interactions between non-pairing nucleotides. Genome wide analysis of inverted repeats flanking circular RNAs confirm that their presence favors circularization, but the overall effect is modest. Together these results suggest that secondary structure considerations alone cannot fully explain backsplicing and that additional interactions are key components of the mechanism.
2024-12-13 | GSE283716 | GEO
Project description:The RNA interference (RNAi) pathway has evolved numerous functionalities in eukaryotes, with many on display in Kingdom Fungi. RNAi can regulate gene expression, facilitate drug resistance, or even be altogether lost to improve virulence potential in some fungal pathogens. In the WHO fungal priority pathogen, Aspergillus fumigatus, the RNAi system is known to be intact and functional. To extend our limited understanding of A. fumigatus RNAi, we performed a sRNA-seq to assess sRNAs produced in several RNAi double knockouts and a wild type strain expressing a 1200 nt inverted-repeat transgene with complementarity to the pksP gene. The transgene harbors a 500-bp inverted repeat. We included an uninduced wild type strain with no inverted-repeat transgene as a control. All conditions were performed in mycelium grown for 24 hours in liquid culture.
2025-01-16 | GSE286229 | GEO
Project description:Loss of function mutations in SMARCB1 are prevalent in pediatric atypical teratoid rhabdoid tumors (ATRTs) and confer an oncogenic dependency on EZH2, providing a compelling rationale for treating these genetically defined cancers via EZH2 inhibition (EZH2i). EZH2i results in tumor regression in SMARCB1-deficient tumors in preclinical studies, but the molecular mechanism has not been fully elucidated. Here we found that the sensitivity of SMARCB1-deficient tumors to EZH2i is associated with the viral mimicry response that depends on both double-stranded RNA (dsRNA) and cytoplasmic DNA sensing pathways. Unlike other epigenetic therapies targeting transcriptional repressors, viral mimicry by EZH2i in SMARCB1-deficient tumors is not triggered by crypt initiation of endogenous retroelements, but rather mediated by increased expression of genes enriched for intronic inverted-repeat Alu (IR-Alu) elements. Interestingly, we found that interferon-stimulated genes (ISGs) are highly enriched for dsRNA-forming intronic IR-Alu elements, suggesting a positive feedback loop whereby interferon response leads to dsRNA formation from intronic ISGs and activation of viral mimicry. Moreover, EZH2i in ATRT cells also enhances the expression of full-length LINE-1 elements, leading to genomic instability and cGAS/STING response in a process dependent on reverse transcriptase activity. Supporting this mechanism, co-depletion of dsRNA sensing and cytoplasmic DNA sensing completely rescues the viral mimicry response to EZH2i in SMARCB1-deficient tumors.
2024-09-05 | GSE213248 | GEO
Project description:Alu SINEs are the most numerous frequently occurring transcription units in our genomes and possess sequence competence for transcription by RNA Pol III. However, through poorly understood mechanisms, the Alu RNA levels are maintained at very low levels in normal somatic cells with obvious benefits of low rates of Alu retrotransposition and energy-economical deployment of RNA Pol III to the tRNA genes which share promoter structure and polymerase requirements with Alu SINEs. Using comparative ChIP sequencing, we unveil that a repeat binding protein, CGGBP1, binds to the transcriptional regulatory regions of Alu SINEs thereby impeding Alu transcription by inhibiting RNA Pol III recruitment. We show that this Alu-silencing depends on growth factor stimulation of cells and subsequent tyrosine phosphorylation of CGGBP1. Importantly, CGGBP1 ensures a sequence-specific discriminative inhibition of RNA Pol III activity at Alu promoters, while sparing the structurally similar tRNA promoters. Our data suggest that CGGBP1 contributes to growth-related transcription by preventing the hijacking of RNA Pol III by Alu SINEs.
2015-04-29 | GSE53571 | GEO
Project description:Origin-Dependent Inverted-Repeat Amplification: Tests of a Model for Inverted DNA Amplification
| PRJNA300521 | ENA