Arabidopsis AGO3 predominantly recruits 24-nucleotide small RNAs to regulate epigenetic silencing [miRNA-seq]
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ABSTRACT: AGO3 predominantly bound 24-nt sRNAs with 5â?? terminal adenine. The spectrum of AGO3-associated sRNAs was different from those bound to AGO2. By contrast, approximately 30% of AGO3-bound 24-nt sRNAs overlapped with those bound to AGO4 and over 60% of AGO3-associated 24-nt sRNA enriched loci were identical to those of AGO4. In addition, expression of AGO3 driven by AGO4 native promoter partially complemented AGO4 function and rescued DNA methylation defect in ago4-1 background. Examination of AGO3 and AGO2 bound small RNAs with/without salt stress.
Project description:AGO3 predominantly bound 24-nt sRNAs with 5â terminal adenine. The spectrum of AGO3-associated sRNAs was different from those bound to AGO2. By contrast, approximately 30% of AGO3-bound 24-nt sRNAs overlapped with those bound to AGO4 and over 60% of AGO3-associated 24-nt sRNA enriched loci were identical to those of AGO4. In addition, expression of AGO3 driven by AGO4 native promoter partially complemented AGO4 function and rescued DNA methylation defect in ago4-1 background. Examination of DNA methylation using bisulfite conversion of unmethylated cytosines in three genetic backgrounds of Arabidopsis thaliana.
Project description:AGO3 predominantly bound 24-nt sRNAs with 5’ terminal adenine. The spectrum of AGO3-associated sRNAs was different from those bound to AGO2. By contrast, approximately 30% of AGO3-bound 24-nt sRNAs overlapped with those bound to AGO4 and over 60% of AGO3-associated 24-nt sRNA enriched loci were identical to those of AGO4. In addition, expression of AGO3 driven by AGO4 native promoter partially complemented AGO4 function and rescued DNA methylation defect in ago4-1 background.
Project description:AGO3 predominantly bound 24-nt sRNAs with 5’ terminal adenine. The spectrum of AGO3-associated sRNAs was different from those bound to AGO2. By contrast, approximately 30% of AGO3-bound 24-nt sRNAs overlapped with those bound to AGO4 and over 60% of AGO3-associated 24-nt sRNA enriched loci were identical to those of AGO4. In addition, expression of AGO3 driven by AGO4 native promoter partially complemented AGO4 function and rescued DNA methylation defect in ago4-1 background.
Project description:Argonaute (AGO) proteins execute Micro-RNA (miRNA) mediated gene silencing. However it is currently debated whether all 4 mammalian AGO proteins (AGO1, AGO2, AGO3 and AGO4) are required for miRNA activity. To address this, we generated a mouse with deleted Ago1, Ago3 and Ago4 genes (Ago134), and found that these Argonaute proteins are completely redundant for miRNA biogenesis, miRNA homeostasis or miRNA function, a role that is carried out exclusively by AGO2. Instead, AGO1/3/4 are required to curtail the expansion of Type-2 adaptive immunity in mice via regulation of precursor-mRNA (pre-mRNA) splicing in CD4+ TH lymphocytes. Gain- and loss-of-function experiments demonstrate that nuclear AGO3 interacts directly with SF3B3, a component of the U2 spliceosome complex, to aid global mRNA splicing. Our work uncouples AGO1, AGO3 and AGO4 from miRNA-mediated RNAi, discovers a new AGO3:SF3B3 complex in the cellular nucleus, and reveals an underappreciated mechanism by which AGO proteins prevent hyper-inflammatory disease.
Project description:Argonaute (AGO) proteins execute Micro-RNA (miRNA) mediated gene silencing. However it is currently debated whether all 4 mammalian AGO proteins (AGO1, AGO2, AGO3 and AGO4) are required for miRNA activity. To address this, we generated a mouse with deleted Ago1, Ago3 and Ago4 genes (Ago134), and found that these Argonaute proteins are completely redundant for miRNA biogenesis, miRNA homeostasis or miRNA function, a role that is carried out exclusively by AGO2. Instead, AGO1/3/4 are required to curtail the expansion of Type-2 adaptive immunity in mice via regulation of precursor-mRNA (pre-mRNA) splicing in CD4+ TH lymphocytes. Gain- and loss-of-function experiments demonstrate that nuclear AGO3 interacts directly with SF3B3, a component of the U2 spliceosome complex, to aid global mRNA splicing. Our work uncouples AGO1, AGO3 and AGO4 from miRNA-mediated RNAi, discovers a new AGO3:SF3B3 complex in the cellular nucleus, and reveals an underappreciated mechanism by which AGO proteins prevent hyper-inflammatory disease.
Project description:Argonaute (AGO) proteins execute Micro-RNA (miRNA) mediated gene silencing. However it is currently debated whether all 4 mammalian AGO proteins (AGO1, AGO2, AGO3 and AGO4) are required for miRNA activity. To address this, we generated a mouse with deleted Ago1, Ago3 and Ago4 genes (Ago134), and found that these Argonaute proteins are completely redundant for miRNA biogenesis, miRNA homeostasis or miRNA function, a role that is carried out exclusively by AGO2. Instead, AGO1/3/4 are required to curtail the expansion of Type-2 adaptive immunity in mice via regulation of precursor-mRNA (pre-mRNA) splicing in CD4+ TH lymphocytes. Gain- and loss-of-function experiments demonstrate that nuclear AGO3 interacts directly with SF3B3, a component of the U2 spliceosome complex, to aid global mRNA splicing. Our work uncouples AGO1, AGO3 and AGO4 from miRNA-mediated RNAi, discovers a new AGO3:SF3B3 complex in the cellular nucleus, and reveals an underappreciated mechanism by which AGO proteins prevent hyper-inflammatory disease.
Project description:Arabidopsis encodes ten ARGONAUTE (AGO) effectors of RNA silencing, canonically loaded with either 21-22nt small RNAs (sRNA) to mediate post-transcriptional-gene-silencing (PTGS) or 24nt sRNAs to promote RNA-directed-DNA-methylation. Using full-locus constructs, we characterized the expression, biochemical properties, and possible modes of action of AGO3. Although AGO3 arose from a recent duplication at the AGO2 locus, their expression differs drastically, with AGO3 prevailing in aerial vascular terminations and specifically in chalazal seed integuments; accordingly, AGO3 down-regulation alters gene expression in siliques. Similar to AGO2, AGO3 binds sRNAs with a strong 5’-adenosine bias, but unlike most Arabidopsis AGOs - AGO2 included - it binds efficiently both 24nt and 21nt sRNAs. AGO3 immuno precipitation experiments in siliques revealed that these sRNAs mostly associate to genes and intergenic regions and not to canonical AGO targets, such as transposable elements. AGO3 localizes to the cytoplasm and co-fractionates with polysomes to possibly mediate PTGS via translation inhibition.
Project description:We sequenced the small RNA bound to AGO4, AGO6 and AGO9 and compared these sRNAs to other libraries isolated such as total sRNAs, ago4 mutant, drd3-1 mutant, an AGO4 D660A slicer mutant and AGO6 and AGO9 under the AGO4 promoter. Keywords: Epigenetics
Project description:The four mammalian Argonaute family members are thought to share redundant functions in the microRNA pathway, yet only AGO2 possesses the catalytic "slicer" function required for RNA interference. Whether AGO1, AGO3, or AGO4 possess specialized functions remains unclear. Here, we Series_summary = show that AGO4 localizes to spermatocyte nuclei during meiotic prophase I, specifically at sites of asynapsis and in the transcriptionally silenced XY sub-domain, the sex body. We generated Ago4 knockout mice and show that Ago4-/- spermatogonia initiate meiosis early, resulting from premature induction of retinoic acid-response genes. During prophase I, the sex body assembles incorrectly in Ago4-/- mice, leading to disrupted meiotic sex chromosome inactivation (MSCI). This is associated with a dramatic loss of microRNAs, >20% of which arise from the X chromosome. Loss of AGO4 results in increased AGO3 in spermatocytes, indicating some degree of redundancy. Thus, AGO4 regulates meiotic entry and MSCI in mammalian germ cells, implicating small RNA pathways in these processes.
Project description:The four mammalian Argonaute family members are thought to share redundant functions in the microRNA pathway, yet only AGO2 possesses the catalytic "slicer" function required for RNA interference. Whether AGO1, AGO3, or AGO4 possess specialized functions remains unclear. Here, we Series_summary = show that AGO4 localizes to spermatocyte nuclei during meiotic prophase I, specifically at sites of asynapsis and in the transcriptionally silenced XY sub-domain, the sex body. We generated Ago4 knockout mice and show that Ago4-/- spermatogonia initiate meiosis early, resulting from premature induction of retinoic acid-response genes. During prophase I, the sex body assembles incorrectly in Ago4-/- mice, leading to disrupted meiotic sex chromosome inactivation (MSCI). This is associated with a dramatic loss of microRNAs, >20% of which arise from the X chromosome. Loss of AGO4 results in increased AGO3 in spermatocytes, indicating some degree of redundancy. Thus, AGO4 regulates meiotic entry and MSCI in mammalian germ cells, implicating small RNA pathways in these processes. mRNA transcripts were isolated and prepared using pachytene spermatocytes, pre-meiotic testes and other tissues from Ago4+/+ and Ago4-/- littermates and sequenced using Illumina HiSeq2000. small RNA transcripts were isolated and prepared using pachytene spermatocytes from adult Ago4+/+ and Ago4-/- littermates and sequenced using Illumina GAII.