Nuclear Role for Human Argonaute-1 as an Estrogen-dependent Transcription Coactivator
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE154279 | GEO | 2020/07/13
REPOSITORIES: GEO
Similar Datasets
Project description:The roles of Argonaute proteins in cytoplasmic miRNA and RNAi pathways are well established. However, their implication in small RNA-mediated transcriptional gene silencing in the mammalian cell nucleus is less understood. We have recently shown that intronic siRNAs cause chromatin modifications that inhibit RNA polymerase II elongation and modulate alternative splicing in an Argonaute-1 (AGO1) dependent manner. Here we used chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) to investigate the genome-wide distribution of AGO1 nuclear targets. Unexpectedly we found that about 80% of AGO1 clusters are associated with cell-type specific transcriptional enhancers, most of them (73%) overlapping active enhancers. This association seems to be mediated by long, rather than short, enhancer RNAs; and to be more prominent in intragenic, rather than intergenic, enhancers. Paradoxically, crossing ChIP-seq with RNA-seq data upon AGO1 depletion revealed that enhancer bound AGO1 is not linked to the global regulation of gene transcription but to the control of constitutive and alternative splicing, which was confirmed by an individual gene analysis explaining how AGO1 controls inclusion levels of the cassette exon 107 in the SYNE2 gene. Genome-wide analysis of AGO-1 and different histone modifications in 2 cell types
2014-09-29 | E-GEOD-56826 | biostudies-arrayexpress
Project description:Small RNAs regulate the genetic networks through a ribonucleoprotein complex called the RNA induced silencing complexes (RISC), which in mammals contains at its center one of four Argonaute proteins (Ago1-4). A key regulatory event in the RNAi and miRNA pathways is Ago loading, where double stranded small RNA duplexes are incorporated into RISC (pre-RISC) and then become single stranded (mature-RISC), a process that is not well understood. The Agos contain an evolutionary conserved PAZ (Piwi/Argonaute/Zwille) domain whose primary function is to bind the 3’-end of small RNAs. We created multiple Paz domain disrupted Ago mutant proteins and studied their biochemical properties and biological functionality in cells. We found that the Paz domain is dispensable for Ago loading of slicing-competent RISC. In contrast, in the absence of slicer activity or slicer substrate duplex RNAs, Paz-disrupted Agos bound duplex siRNAs but were unable to unwind/eject the passenger strand and form functional RISC complexes. We have discovered that the highly conserved Paz domain plays an important role in RISC activation, providing new mechanistic insights into how miRNAs regulate genes, as well as new insights for future design of miRNA and RNAi-based therapeutics. Various Argonautes associated small RNA profiles were generated by deep sequencing the Agos-IP samples in HEK293 Cells transfected with corresponding Argonaute.
2012-07-12 | E-GEOD-39146 | biostudies-arrayexpress
Project description:Small-RNA (sRNA)-guided transcriptional gene silencing by Argonaute (Ago)-containing complexes is fundamental to genome integrity and epigenetic inheritance. The RNA cleavage (“Slicer”) activity of Argonaute has been implicated in both sRNA maturation and target RNA cleavage. Typically, Argonaute slices and releases the passenger strand of duplex sRNA to generate active silencing complexes, but it remains unclear whether slicing of target nascent RNAs, or other RNAi components, also contributes to downstream transcriptional silencing. Here, we develop a strategy for loading the fission yeast Ago1 with a single-stranded sRNA guide, which bypasses the requirement for slicer activity in generation of active silencing complexes. We show that slicer-defective Ago1 can mediate secondary sRNA generation, H3K9 methylation, and silencing similar to or better than wild-type and associates with chromatin more efficiently. The results define an ancient and minimal sRNA-mediated chromatin silencing mechanism, which resembles the germline-specific sRNA-dependent transcriptional silencing pathways in Drosophila and mammals. This SuperSeries is composed of the SubSeries listed below.
2016-12-19 | GSE81734 | GEO
Project description:The roles of Argonaute proteins in cytoplasmic miRNA and RNAi pathways are well established. However, their implication in small RNA-mediated transcriptional gene silencing in the mammalian cell nucleus is less understood. We have recently shown that intronic siRNAs cause chromatin modifications that inhibit RNA polymerase II elongation and modulate alternative splicing in an Argonaute-1 (AGO1) dependent manner. Here we used chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) to investigate the genome-wide distribution of AGO1 nuclear targets. Unexpectedly we found that about 80% of AGO1 clusters are associated with cell-type specific transcriptional enhancers, most of them (73%) overlapping active enhancers. This association seems to be mediated by long, rather than short, enhancer RNAs; and to be more prominent in intragenic, rather than intergenic, enhancers. Paradoxically, crossing ChIP-seq with RNA-seq data upon AGO1 depletion revealed that enhancer bound AGO1 is not linked to the global regulation of gene transcription but to the control of constitutive and alternative splicing, which was confirmed by an individual gene analysis explaining how AGO1 controls inclusion levels of the cassette exon 107 in the SYNE2 gene.
2014-09-29 | GSE56826 | GEO
Project description:Small non-coding RNAs function in concert with Argonaute (Ago) proteins to regulate gene expression at the level of transcription, mRNA stability or translation. Ago proteins bind small RNAs and form the core of silencing complexes. Here we report the analysis of small RNAs associated with human Ago1 and Ago2 revealed by immunoprecipitation and deep sequencing. Among the reads we find small RNAs originating from the small nucleolar RNA (snoRNA) ACA45. Moreover, processing of ACA45 requires Dicer activity but is independent of Drosha/DGCR8. Using bio-informatic prediction algorithms and luciferase reporter assays, we uncover the mediator subunit CDC2L6 as one potential mRNA target of ACA45 small RNAs suggesting a role for ACA45 processing products in post-transcriptional gene silencing. We further identify a number of human snoRNAs with microRNA (miRNA)- like processing signatures. We have therefore identified a novel class of small RNAs in human cells that originate from snoRNAs and can function like miRNAs. Two samples examined. Small RNAs associated to human Argonaute 1 and human Argonaute 2
2008-11-20 | E-GEOD-13370 | biostudies-arrayexpress
Project description:microRNAs (miRNAs) are small non-coding RNAs that function in literally all cellular processes. miRNAs interact with Argonaute (Ago) proteins and guide them to specific target sites located in the 3’ untranslated region (UTR) of target mRNAs leading to translational repression and deadenylation-induced mRNA degradation. Most miRNAs are processed from hairpin-structured precursors by the consecutive action of the RNase III enzymes Drosha and Dicer. However, processing of miR-451 is Dicer-independent and cleavage is mediated by the endonuclease Ago2. Here we have characterized miR-451 sequence and structure requirements for processing as well as sorting of miRNAs into different Ago proteins. Pre-miR-451 appears to be optimized for Ago2 cleavage and changes result in reduced processing. In addition, we show that the mature miR-451 only associates with Ago2 suggesting that mature miRNAs are not exchanged between different members of the Ago protein family. Based on cloning and deep sequencing of endogenous miRNAs associated with Ago1-3, we do not find evidence for miRNA sorting in human cells. However, Ago identity appears to influence the length of some miRNAs, while others remain unaffected. Examination of miRNAs associated with endogenous human Ago1-4 in HeLa cells
2013-03-29 | E-GEOD-45506 | biostudies-arrayexpress
Project description:While Argonaute (AGO) proteins play a major role in transcriptional gene silencing (TGS) in many organisms, their role in the nucleus of somatic mammalian cells remains elusive. Here, we have purified AGO1 and AGO2 chromatin-embedded complexes, and found these proteins associated with previously described partners, but also with chromatin modifiers and, rather unexpectedly, with different splicing factors. Using the CD44 gene as a model for alternative splicing, we show that both AGO1 and AGO2 are required for Protein Kinase C (PKC)-dependent variant exon inclusion. AGO proteins facilitate the spliceosome recruitment and modulate the elongation rate of RNA polymerase II (RNAPII). The recruitment of AGO proteins to CD44 transcribed region is dependent on both the endonuclease Dicer and the chromodomain-containing protein HP1g, and results in locally increased levels of histone H3 lysine 9 (H3K9) methylation on variant exons. Genome wide analysis of splicing in either AGO2 or Dicer null cells showed that the two proteins have similar effects on many splicing events. Finally, sRNAs associated with nuclear AGO2 are mostly in sense orientation relative to protein-coding genes, supporting a role for intragenic antisense non-coding RNAs in the recruitment AGO and splicing factors. Together, our data demonstrate for the first time that the endogenous RNAi pathway is involved in alternative splicing decisions, unravelling a new model in which AGO proteins couple RNAPII elongation and chromatin modification. Deep sequencing of small RNAs (approx. 15-80 nucleotides) bound to either cytoplasmic or chromatin-associated AGO2 complex.
2012-09-10 | E-GEOD-39748 | biostudies-arrayexpress
Project description:Drosophila Argonaute-1 and Argonaute-2 differ in function and small RNA content. AGO2 binds to siRNAs, whereas AGO1 is almost exclusively occupied by microRNAs. microRNA duplexes are intrinsically asymmetric, with one strand, the miR strand, preferentially entering AGO1 to recognize and regulate the expression of target mRNAs. The other strand, miR*, has been viewed as a by-product of microRNA biogenesis. Here, we show that miR*s are often loaded as functional species into AGO2. This indicates that each microRNA precursor can potentially produce two mature small RNA strands that are differentially sorted within the RNAi pathway. miR* biogenesis depends upon the canonical microRNA pathway, but loading into AGO2 is mediated by factors traditionally dedicated to siRNAs. By inferring and validating hierarchical rules that predict differential AGO loading, we find that intrinsic determinants, including structural and thermodynamic properties of the processed duplex, regulate the fate of each RNA strand within the RNAi pathway. These were independently processed and sequenced using the Illumina GAII platform. In total, five libraries were analyzed.
2009-11-15 | E-GEOD-17734 | biostudies-arrayexpress
Project description:Small RNAs regulate the genetic networks through a ribonucleoprotein complex called the RNA induced silencing complexes (RISC), which in mammals contains at its center one of four Argonaute proteins (Ago1-4). A key regulatory event in the RNAi and miRNA pathways is Ago loading, where double stranded small RNA duplexes are incorporated into RISC (pre-RISC) and then become single stranded (mature-RISC), a process that is not well understood. The Agos contain an evolutionary conserved PAZ (Piwi/Argonaute/Zwille) domain whose primary function is to bind the 3’-end of small RNAs. We created multiple Paz domain disrupted Ago mutant proteins and studied their biochemical properties and biological functionality in cells. We found that the Paz domain is dispensable for Ago loading of slicing-competent RISC. In contrast, in the absence of slicer activity or slicer substrate duplex RNAs, Paz-disrupted Agos bound duplex siRNAs but were unable to unwind/eject the passenger strand and form functional RISC complexes. We have discovered that the highly conserved Paz domain plays an important role in RISC activation, providing new mechanistic insights into how miRNAs regulate genes, as well as new insights for future design of miRNA and RNAi-based therapeutics.
2012-07-12 | GSE39146 | GEO
Project description:The core components of RNA silencing effector complexes include small RNAs and members of the Argonaute (AGO) protein family. Arabidopsis encodes ten AGOs and complex population of small RNAs. It remains largely unknown how these small RNAs are recognized and recruited by each AGO complex. Here we purified four AGO complexes and identified small RNAs in each complex by deep sequencing. Keywords: Small RNA sorting Small RNAs were prepared from Arabidopsis AGO1, AGO2, AGO4 and AGO5 complexes, ligated to a 3' adaptor and a 5' acceptor sequentially, and then RT-PCR amplified. PCR products were reamplified using a pair of solexa cloning primers and then provided for sequencing. For technical details, see Qi, Y., He, X., Wang, X.J., Kohany, O., Jurka, J., and Hannon, G.J. 2006. Distinct catalytic and non-catalytic roles of ARGONAUTE4 in RNA-directed DNA methylation. Nature 443(7114): 1008-1012.
2008-04-05 | E-GEOD-10036 | biostudies-arrayexpress