The exonuclease ERI-1 has a conserved dual role in 5.8S rRNA processing and RNAi
ABSTRACT The exonuclease ERI-1 negatively regulates RNA interference in Caenorhabditis elegans and Schizosaccharomyces pombe, and is required for production of some C. elegans endogenous small interfering RNAs. We show that ERI-1 performs 3' end processing of the 5.8S ribosomal RNA in both C. elegans and S. pombe. In C. elegans, two protein isoforms of ERI-1 are localized to the cytoplasm, and each has distinct functions in ribosomal RNA processing and negative regulation of RNA interference.
Full-textDOI: · Available from: Harrison W Gabel, Jul 16, 2015
- SourceAvailable from: Nuria Morral
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- "Exonuclease Eri-1 (enhanced RNAi) has been reported to have negative regulatory effects on RNAi (Gabel and Ruvkun , 2008). Eri-1 can degrade the 3¢ end of siRNA and histone mRNA in Caenorhabditis elegans, humans, and fission yeast (Hong et al., 2005; Gabel and Ruvkun, 2008). Administration of high doses of siRNA induces Eri-1 expression in mice (Hong et al., 2005). "
ABSTRACT: RNA interference (RNAi) has become the cornerstone technology for studying gene function in mammalian cells. In addition, it is a promising therapeutic treatment for multiple human diseases. Virus-mediated constitutive expression of short hairpin RNA (shRNA) has the potential to provide a permanent source of silencing molecules to tissues, and it is being devised as a strategy for the treatment of liver conditions such as hepatitis B and hepatitis C virus infection. Unintended interaction between silencing molecules and cellular components, leading to toxic effects, has been described in vitro. Despite the enormous interest in using the RNAi technology for in vivo applications, little is known about the safety of constitutively expressing shRNA for multiple weeks. Here we report the effects of in vivo shRNA expression, using helper-dependent adenoviral vectors. We show that gene-specific knockdown is maintained for at least 6 weeks after injection of 1 × 10(11) viral particles. Nonetheless, accumulation of mature shRNA molecules was observed up to weeks 3 and 4, and then declined gradually, suggesting the buildup of mature shRNA molecules induced cell death with concomitant loss of viral DNA and shRNA expression. No evidence of well-characterized innate immunity activation (such as interferon production) or saturation of the exportin-5 pathway was observed. Overall, our data suggest constitutive expression of shRNA results in accumulation of mature shRNA molecules, inducing cellular toxicity at late time points, despite the presence of gene silencing.Human gene therapy 07/2011; 22(12):1483-97. DOI:10.1089/hum.2010.234 · 3.62 Impact Factor
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- "The other category comprises gene homologues of ERI1. Apart from its role in the destruction of siRNA, ERI1 is also involved in 5.8S ribosomal RNA processing (Ansel et al., 2008; Gabel and Ruvkun, 2008). The absence of this protein may explain in part why silencing may persist almost indefinitely in some Phytophthora species in the absence of the primary silencing signal (Gaulin et al., 2007; van West et al., 1999). "
ABSTRACT: Gene silencing may have a direct or indirect impact on many biological processes in eukaryotic cells, and is a useful tool for the determination of the roles of specific genes. In this article, we report silencing in Phytophthora infestans, an oomycete pathogen of potato and tomato. Gene silencing is known to occur in P. infestans, but its genetic basis has yet to be determined. Genes encoding the major components of the RNA interference (RNAi) pathway, Dicer-like (Pidcl1), Argonaute (Piago1-5) and RNA-directed RNA polymerase (Pirdr1), were identified in the P. infestans genome by comparative genomics, together with families of other genes potentially involved in gene silencing, such as histone deacetylases, histone methyltransferases, DEAD helicases, chromodomain proteins and a class 1 RNaseIII. Real-time reverse transcription-polymerase chain reaction demonstrated transcript accumulation for all candidate genes throughout the asexual lifecycle and plant infection, but at different levels of mRNA abundance. A functional assay was developed in which silencing of the sporulation-associated Picdc14 gene was released by the treatment of protoplasts with in vitro-synthesized double-stranded RNAs homologous to Pidcl1, Piago1/2 and histone deacetylase Pihda1. These results suggest that the components of gene silencing, namely Dicer-like, Argonaute and histone deacetylase, are functional in P. infestans. Our data demonstrate that this oomycete possesses canonical gene silencing pathways similar to those of other eukaryotes.Molecular Plant Pathology 03/2011; 12(8):772-85. DOI:10.1111/j.1364-3703.2011.00710.x · 4.49 Impact Factor
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- "These roles for RRF-3 in endogenous gene regulation and in exo RNAi efficacy are shared with a group of factors in the ERI pathway (so named because of Enhanced RNAi phenotypes). These include the widely conserved exoribonuclease and DCR-1 complex member ERI-1, the uncharacterized Dicer complex member ERI-9, DCR-1 itself, and the Argonaute ERGO-1 (Asikainen et al., 2007; Duchaine et al., 2006; Gabel and Ruvkun, 2008; Gent et al., 2009; Kennedy et al., 2004; Pavelec et al., 2009). All of these factors appear to have somatic roles, as their activity in siRNA production modulates the subcellular localization of a somatically expressed Argonaute NRDE-3, and their mutations increase efficacy of exo RNAi against somatic genes. "
ABSTRACT: Endogenous RNA-directed RNA polymerases (RdRPs) are cellular components capable of synthesizing new complementary RNAs from existing RNA templates. We present evidence for successive engagement of two different RdRPs in an endogenous siRNA-based mechanism targeting specific mRNAs in C. elegans soma. In the initiation stage of this process, a group of mRNA species are chosen as targets for downregulation, leading to accumulation of rare 26 nt 5'-phosphorylated antisense RNAs that depend on the RdRP homolog RRF-3, the Argonaute ERGO-1, DICER, and a series of associated ("ERI") factors. This primary process leads to production of a much more abundant class of 22 nt antisense RNAs, dependent on a secondary RdRP (RRF-1) and associating with at least one distinct Argonaute (NRDE-3). The requirement for two RdRP/Argonaute combinations and initiation by a rare class of uniquely structured siRNAs in this pathway illustrate the caution and flexibility used as biological systems exploit the physiological copying of RNA.Molecular cell 03/2010; 37(5):679-89. DOI:10.1016/j.molcel.2010.01.012 · 14.46 Impact Factor