Article

The exonuclease ERI-1 has a conserved dual role in 5.8S rRNA processing and RNAi

Department of Genetics, Harvard Medical School, and Department of Molecular Biology, Massachusetts General Hospital, CPZN7250, 185 Cambridge Street, Boston, Massachusetts 02114, USA.
Nature Structural & Molecular Biology (Impact Factor: 11.63). 06/2008; 15(5):531-3. DOI: 10.1038/nsmb.1411
Source: PubMed

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.

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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). "
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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). "
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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. "
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