Topic
RNAi effector complex
About: RNAi effector complex is a research topic. Over the lifetime, 8 publications have been published within this topic receiving 2388 citations.
Papers
TL;DR: The purification of an RNAi effector complex termed RITS (RNA-induced initiation of transcriptional gene silencing) that is required for heterochromatin assembly in fission yeast is described and a mechanism for the role of the RNAi machinery and small RNAs in targeting of heterochROMatin complexes and epigenetic genesilencing at specific chromosomal loci is suggested.
Abstract: RNA interference (RNAi) is a widespread silencing mechanism that acts at both the posttranscriptional and transcriptional levels. Here, we describe the purification of an RNAi effector complex termed RITS (RNA-induced initiation of transcriptional gene silencing) that is required for heterochromatin assembly in fission yeast. The RITS complex contains Ago1 (the fission yeast Argonaute homolog), Chp1 (a heterochromatin-associated chromodomain protein), and Tas3 (a novel protein). In addition, the complex contains small RNAs that require the Dicer ribonuclease for their production. These small RNAs are homologous to centromeric repeats and are required for the localization of RITS to heterochromatic domains. The results suggest a mechanism for the role of the RNAi machinery and small RNAs in targeting of heterochromatin complexes and epigenetic gene silencing at specific chromosomal loci.
1,384 citations
TL;DR: It is demonstrated that recombinant, human Argonaute2 can combine with a small interfering RNA (siRNA) to form minimal RISC that accurately cleaves substrate RNAs and provide a source of recombinant enzyme for detailed biochemical studies of the RNAi effector complex.
Abstract: Genetic, biochemical and structural studies have implicated Argonaute proteins as the catalytic core of the RNAi effector complex, RISC. Here we show that recombinant, human Argonaute2 can combine with a small interfering RNA (siRNA) to form minimal RISC that accurately cleaves substrate RNAs. Recombinant RISC shows many of the properties of RISC purified from human or Drosophila melanogaster cells but also has surprising features. It shows no stimulation by ATP, suggesting that factors promoting product release are missing from the recombinant enzyme. The active site is made up of a unique Asp-Asp-His (DDH) motif. In the RISC reconstitution system, the siRNA 5' phosphate is important for the stability and the fidelity of the complex but is not essential for the creation of an active enzyme. These studies demonstrate that Argonaute proteins catalyze mRNA cleavage within RISC and provide a source of recombinant enzyme for detailed biochemical studies of the RNAi effector complex.
850 citations
TL;DR: The recent findings showing that non-coding RNAs and heterochromatin play important roles in dynamic regulation of genomes, which has important implications for human health and disease are presented.
Abstract: Heterochromatin assembly involving posttranslational modifications of histones is critical for various chromosomal processes including the regulation of gene expression and the maintenance of genomic integrity. Defective heterochromatin formation has been linked to cancer. Our previous work has shown that non-coding RNAs and the RNAi machinery, involved in the processing of non-coding RNAs, play prominent roles in the assembly of heterochromatin structures. Indeed, the loss of factors involved in RNAi such as Argonaute, Dicer and RNA-dependent RNA polymerase cause severe defects in centromeric heterochromatin formation, leading to missegregation of chromosomes during cell division. An Argonaute-containing RNAi effector complex named RITS has been identified that facilitates the loading of a conserved histone methyltransferase Clr4/Suv39h, which is essential for heterochromatin assembly. We have recently discovered an unexpected role for heterochromatin factors in the RNA quality control. Heterochromatin factors localize broadly across the genome and collaborate with RNAi machinery to suppress potentially deleterious RNAs, the uncontrolled accumulation of which can cause DNA damage and modify epigenetic genomic profiles. I will present our recent findings showing that non-coding RNAs and heterochromatin play important roles in dynamic regulation of genomes, which has important implications for human health and disease. Citation Format: Shiv Grewal. Epigenetic genome control by heterochromatin machinery and non-coding RNAs [abstract]. In: Proceedings of the AACR Special Conference on Noncoding RNAs and Cancer; 2012 Jan 8-11; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(2 Suppl):Abstract nr IA5.
1 citations
TL;DR: Findings in Drosophila suggest that dFMR1 functions in an RNAi-related process to regulate the expression of its target genes at the level of translation (protein synthesis), and demonstrates that RISCs could provide a platform through which FMRP1 can act.
TL;DR: Two independent research groups have demonstrated in Drosophila that one of the components of the RNAi pathway is dFMR1 (also known as dFXR), the homologue of the human fragile-X mental-retardation protein, which suggests that RISCs might provide a platform via which FMRP1 can act.
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 1 |
| 2013 | 1 |
| 2012 | 1 |
| 2005 | 2 |
| 2004 | 1 |
| 2002 | 2 |